'90 Camaro RS Stalling

I have a '90 Camaro RS with a rebuilt engine. After rebuilding the engine I had a new exhaust installed but it turns out that the exhaust they installed wasn't designed for the Camaro, so they customized it to fit. I later found out that they also left out the catalytic converter. The car ran fine for a while but now it stalls after driving for a short time. A few times it even backfired. I read a few post with similar problems and a few people said that it could be restricted exhaust. I also read a few post replies that mentioned tps. I'm not sure what that is. Any advice on my problem would be appreciated.

usually the place that an exhaust commonly clogs is in the cat, which you don't have, so that pretty much elimates that.

TPS = Throttle Position Sensor
It is possible that the problem is unrelated to the rebuild... Lets assume this is the case... Has your car thrown any trouble codes?
If we assume the problem to be unrelated to the rebuild, then we would have to assume the problem is a bad sensor... Maybe O2, MAP, or MAF sensor...

I almost hate to say this but I'm not too sure what you mean by trouble codes. However I did notice that when you turn the wheel all the way to both the left and right the car turns off. Also I don't know if I mentioned this but the car runs and I noticed that when I start to slow or come to a stop all I have to do is put the car in neutral and its fine.

To check your trouble codes, follow the directions at
http://www.thirdgen.org/service-engine-light-error-codes (http://www.thirdgen.org/service-engine-light-error-codes)
The 12 pin DLC connector is located under the steering wheel on the dash on the driver side... code 12 is the default telling you the system is functioning, each code will blink 3 times, write down all, if any, codes your car 'service engine soon' light blinks off and let us know.
Good luck