I have an 88' iroc with a 350. the fuel gauge didn't work when I bought the car but it does peg when the car is running. Someone already saved me the trouble of getting to the tank by cutting through the floor. Is this a common problem? any advice is helpful thanks

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Which way does it peg full or empty?

the gauge pegs full and the car runs. I have a lot of trouble when it's cold though. could that be related?

Well the way the gauge works is like kind of a tug of war between the gauges internal resistance and the fuel gauge sender which runs for 0-90 ohms. 0 being empty and 90 being full. Now as long as the sensor remains in the range of 0-90 ohms the needle will sweep from full to empty. However assuming the gauge is good what most likely happened is you have a broken wire or a bad connection to the fuel level sensor which basically makes your fuel level sensors resistance to the gauge anyways look like infinitely larger resistance (which is far beyond the max 90 ohms lol). This will force the gauge to just peg to the max. An easy way to diagnose all this is take apart the dash and measure the resistance to ground where the gauge plugs in.

ok so that solves my gauge problem. the next issue i have is cold starts. the car with start up immediately but ill not idle, you almost have to keep the car at 1500-2000 rpm just to warm up for a while then baby it for the first few minutes you drive it. how can i check the cold start injector is working right?

and the pcv valve and hose was removed and the hole in the valve cover has been taped over. how will this affect performance?

Well first do you have any check engine codes? The cold start valve is an easy one to check you will need a fuel pressure gauge though. All you do is when the car is dead cold disconnect the 4 pronged EST connector at the distributor (very important), hook up the fuel pressure gauge, put the car in run for a second or to (note gauge reading), and then while watching the gauge have someone crank the car over. The fuel pressure should drop by no less than 3 psi will most likely drop a lot more since its pretty cold out. If it does not drop the cold start injector system is not working and needs to be diagnosed further. Although if it has to be reved up for something like a whole minute or so i don't think its the cold start injector as they are only supposed to ease starting once started the ECM should take over. Wouldn't hurt to check it out though as its an easy thing to do anyways. As far as the PVC valve i would definitely look into hooking that back up. Its purpose as well as reducing emissions is to keep the oil clean by removing blow by gasses from the crank case. If deleted properly it shouldn't make any difference that the ECM couldn't account for anyways.

I don't have any check engine lights. Although the car has edelbrock headers and a cat delete if that has anything to do with it. and once the car is warm there are absolutely no problems

Well i would again check the cold start valve no harm in it. Then i would start too look at a vacuum leak, bad IAC valve or plugged ports, bad coolant/air temp sensor for the ecm not the gauge, fuel pressure stuff like that. You wouldn't by chance have access to a scanner would you? The other thing is even though you have no check engine light i would still try and ring out the codes because sometimes there may be a stored code with no light and from hearing that theres no cat and the PVCs eliminated i find it hard to imagine that kinda stuff would be done and other emissions stuff ( like the EGR valve for example a real popular one) which would throw a code if removed hadn't been done.

I have a set of summit pod gauges for air/fuel, temp and voltage that are all accurate and work so I'm not sure why the dash temp gauge doesn't work. And I've ruled out the cold start injector being a problem, my air filters were clogged. Surprisingly the car runs better with the MAF unplugged.. and I don't get a check engine light. Also I found a small yellow wire with some weird plug and spring combo.

when you removed the pcv valve and hose did you block off the nipple on the baseplate?
if not, major vaccumm leak...

here's the deal, I didn't modify anything. I've had the car for 2 weeks tops and I'm trying to fix the few things wrong before I send it.

Gotcha, car was like that when you got it. Like others have said, replace the pcv valve, that will probably solve your idle issues as I suspect a vac leak.
As for the fuel guage, the float and sending unit are in the tank, check to see that the float is not hung up on something. If someone has already cut a hole in the back, the fuel pump has probably been replaced, it may have been installed improperly.

hey i am having the same problem with my fuel level gauge... mine is pegged way past the full mark... like its pointing at 3o'clock... any suggestions?

most likly the sending unit in the tank, they go from time to time

If anyone wanted to know, the fuel gauge was a loose ground wire that someone cut putting in a sound system. The second problem with the cold start was the MAF didn't work because it was clogged, the car had a timing issue and the check engine light didn't work. A scanner showed the MAF as problematic.

where was your wire loose at? where is it grounded to? Thanks

Yeah where was it grounded? Im having the same problem you did.