Guys, I need some help with this badly

Keep in mind that all the parts I have installed or replaced were specific to the year, make and model of this car.

For starters I have a basic stock 1991 z28 with the 5.7 tpi that wouldn't pass emissions so I put a whole new exhaust system on it (Edlebrock headers, High flow cats and Borla Exhaust all Stainless). I also tuned it up with new plugs (bosch platnium) cap - rotor, 8mm wires, K&N air filters, new O2 sensor, new Mallory fuel pump and filter and new Throttle position sensor. She has been sitting for some time (almost a year) so I did have old gas in her and she was very doggy before I performed all the above items.

Here is the part I don't get, she will run like a champ until the car gets to normal operating temp and then she will fall flat on her face (no power and idles like she has a massive cam). I have checked the fuel pressure and it is at 42 with key on and 38 to 39 running. It is throwing no codes from the computer but my brand new cats are glowing red after trying to operate with the miss (these are brand new so I can't believe that they are plugged). I have checked all the injectors and they are running perfectly according to my gauge.

I have tried to disconnect the exhaust completely and run directly off the headers, no difference. I have checked the fuel pressure regulator and no evidence of gas in the vacum line so leads me to belive the diaphram is not leaking.

I have been told by some that I need to run bigger injectors and a variable fuel regulator because of the headers, or I need a programed chip for my car, or my computer is dead. I have already spent more than I planned and it is nickle and diming me to death.

Anybody with ideas please let me know because I love my car but if this keeps up it will be the death of me, and my third gen.

 

i believe red cats mean either there plugged or your running lean

 

I belive it is running lean but my problem is what is causing it, I am sure these new cats are not plugged.

 

what size injectors when its cold its running a richer cycle then when its warm you should datalog it and richen it up or buy a chip

 

Problem solved.... It was finally determined that my number 3 injector was throwing off the fuel delivery. I had checked and rechecked these injectors many times but apparently this one had a mind of its own (it would work when it wanted to) So as it goes my third gen is now stored for the winter and now I will have to wait and see how many mustangs I can eat next year... BETTER LATE THAN NEVER!!!!!!!!!!!!!!!

 

I had same issue, replaced just as much stuff, spent $300 in towing due to it dying when it was warm after I thought things were running good. Mechanics had the intake off a few times, the computer replaced, they were scratching their heads as much as I was till one mechanic finally put a node light on one of the injectors and noticed the weak signal. i had two bad injectors, and according to the mechanic, it put a draw or resistance on all the injectors. This had killed an entire summer before it was resolved. It's kind of enlightening to hear the same scenario from a different source... Glad you found your issue as soon as you did!