Bear in mind that I am not a Geo fan or expert! But there are things that are pretty common in all internal combustion engines! They are fuel and air in, compression, explosion (starting power stroke),and exhausting burned fuel remains as well as carbon-dioxide and other burned vapors into the air! Any major changes in any of these is going to greatly affect how engine runs, as well as how much power it puts forth! Breaking it down to simplest one word per operation -- we get "in,- explosion,- exhaust"! These are all timed to arrive at the right spot at the right time!

How well the engine breathes affects how well the engine runs (and how much power output you get)!! So you start by checking to see that the air coming in is un-restricted..
Generally speaking you want to make sure that the air filter is clean, and entry into air filter enclosure is not restricted (or blocked)-- Next you want to make sure that the fuel is delivered properly! Many of modern engines have fuel injection, and other than basic checks there isn't a lot you can do to fix this, unless you know a lot about fuel injection system(s)! - Back in the "old days", they used carbureters, and there were tricks that could be used to change things slightly,-- and verify that it all was working right! Now if it starts ok, and runs at highway speed (after you get it up to that speed)-- if it does not "bottom out and seem to be runing out of gas almost, -- most likely fuel to carb, - or inj. system is ok! Next thing is ignition timing!-- With modern electronic ignition
this is pretty well un-chaning - as long as you timing of camshaft and engine have not had things apart in that timing system! This brings us to next very imprtant thing!
What is the compression! If you have valves that are to tight (and leaking)- this referrs to the "seal" between valve and valve seats!! if you have a burned valve, or valves need adjusted, you then do not have power on whatever cylinder is leaking, - this affects both air fuel mixture coming in, and compression, and power from explosion of gas in cylinder! So getting a compression gauge, or having somebody check at a garage is a good idea!
Remember I mentined breathing?-- Well if it doesn't come in good, it is not going to be "delivering good" either! Don't forget that exhause could be giving probelms too if pipe smashed h shut, - or catylitic convewrter is plugged up! And of course there are the sparkplugs.... I am assuming that you checked and verified that you have right "gap" on each one! "Pregapped" written on box means nothing, it does not compensate for sparkplugs dropped on cement floor, (and gaps pounded shut), 60- some years of experience has taught me a that just because it is a new part in a new box, -- does not mean that it is a good part! -- Did it run worse after you did the "tuneup" or better?? You could have taken out properly functioning part and put in one that does not work! Also how good are your wires to plugs?? The
"modern" resistor sparkplug "wires" do not have wire in them! They have a fabric or synthetic fiber core with carbon twisted inside,- then coverd with insulating "rubber"- (actually very flexible plastic compounds most of the time)! You coud have a bad wire,- which makes plug miss,- deliver very poor ignition of gasses in cylinder,- or not "fire plug" at all! These things are somewhat delicate, and are easily damaged when changing plugs (if you are not really careful)! You can start up engine with one wire removed, and hanging loose, and see if engine runs worse,- or the same.. If it is worse then that cylinder is firing ok, - move on to the next! Always remove and install wires with engine shut off (unless you are experienced at doing this),- because that 60,000+ volts will knock the hell out of you and possibly cause you to injure yourself on something jerking back to get away)! Note here that loss of power in one cylinder will reduce the power engine has by at least 1/3!.. some engines will feel more like only half there!!

Now, - if you have a little mechanical ability, and want to save yourself a lot of money, -- I reccomend that you go down to a "quality car parts supply store"_,-(like "Auto Zone" for instance),-- and buy yourself a "Haynes Auto Repair" manual that is made for your year and model car! Do not buy a Chilton's -- even if they tell you "it is as good",- (or better than Haynes)! This book covers just about everything in your car (except rebuilding transmission)! Has parts breakdown and repair, rebuild,-adjust infomation,- and tons of illustration,- so you can identify unfarmiliar thihngs when looking for problems! .. If you do not have a "good Geo mechanic" that you have service done by,-- any gareage will appreciate this manual, and it might a save you money there too,- because they may not break something taking it apart, (or adjusting properly)! You can buy a few "cheap- essential tools" to do a whole lot of work yourself for probably less than one trip to to Cheverolet for any kind of maintainance by "Mr Good-Pliers"!

Ive checked the compression 1,2,+4 are 175, 3 is 150,
the exhaust blows strong and the cat converter looks like new
and the air filter is very clean.

thanks for the help ill go right to checking everything else you have mentioned

Well it sounds like you have the makings to allow proper opearation! At least compression is good enough for that, --there is still ignition timing, to worry about, if this one has a fabric timing belt, (and I am guessing it does)! Then the possibility of being off one "tooth" on teh belt is possible! More than that and it probably won't run well enough to pull the car! Also you may have a malfunctioining electronic sensor that is making the engine run bad (through ECU) "so it does not get damaged??"

So consider computer (ECU)setup when everything else seems to check out right--- you may ba able to get a "computer diganostic check" at Auto zone,--I use this as example,- because I have experience with Auto Zone,- I am sure lots of other will do this free also! Or after all else fails, you can pay somebody for a complete computer diagnostic check,- if you can not find anybody to do it for free!... This will tell you if yhou have any malfunctionoing sensors, and if the ECU is functioning properly (or capable of functinoing properly)!

Now there is one last "trick" available, -- that is to diconnect one battery cable for a few seconds (I myself would leave it off for a couple minutes),-- this causes the residual electricity to dissipate from circuitry, and the memory on in the ECU will be lost! (This is essentioally the same as re-booting your PC)! Now go out aand drive treh car normally, and it will re-program itself from the default settings to operate right with your car... BUT be aware that you do not have a radio that "locks up" if stolen-- so that it will not work for theif!! I doubt that your car would have had one from factory,--- but if you have some kind of "high buck special" with theft proofing circuitry, it could refuse to work until you gert the "code" to unlock it again! It can be a hassle to get the code so you can "unlock" and use again! This is used sometims to get "service light" to shut off in dash! They have occasionally came on though there really is not a problem!!!

Now I have given away "high buck secrets" of the "riop-off auto shop business"! So always be carfeful of who you have work on your car!! I have had my wife have problems away from home, and get a "quick fix" somewhere, and then not only have to fix the origional problem, but also the stuff they ruined "fixing it" to limp back home! Majority will not do this however!