1991 Pontiac Firebird Engine running badly

I've had this car for about a year now with no problems at all. Then engine was rebuilt so it has only 83000 miles on it. A little while ago it started having a problem. It ran fine, I didn't really drive it that much. One day I was driving it a lot though, a lot more than I usually would. It was very hot that day and the engine temp got up to about 220, a little over that. Much higher than usual because of all the driving. That night after I shut it off for a little bit, then came out and turned it back on it started running horribly. It sounded like it wasn't getting enough fuel. It sounded like it was missing at idle and when I pushed on the gas a little it would rev up to about 1500 rpms, then die or begin to die. The next day after it had cooled off, it ran fine. When I drove it somewhere and let it sit, came back out and tried to start it again, it had the same problem. It started, but when I try and rev it, it would die. The problem has gotten worse, it won't even drive one place now before it runs bad. It will do it at idle now and wheneber I start it. I replaced the tps, not it. The IAC is fine. It idles high now, around 2000 rpms at park and if I let it sit for a minute or two while running, the rpms drop to 700-1000. It will rev up to about 3500-4000 in park, then die again or begin to die. If I rev it and hold it at 3500-4000 rpms for a mintue or two, then let off the gas completely it will die or almost stall. It sounds like its just guessing on the engine fuel and other things until its at a constant, then when hte constant is broken it doesn't know what to do and dies as a result. Checked fuel pump, not it. No codes flashing.