1988 GTA 5.7 Vortec motor. When the problem first occured I drove the car around the block and it barely left 1st gear and limped back home had no response. The car has always shot up to 3500 rpms around 72 mph and randomly thrown a check engine light that goes away in minutes. Car would occasionally run like it was struggling on long drives recently. I tried to check for code but its so subtle it wasnt stored and I cannot duplicate it. Spark in all cylinders. Fuel at rail 43.5 PSI. Engines new with 11,000, new spark plugs for a vortec motor, new wires, distributor, ingition coil, injectors, fuel pump relay, adjustable fuel pressure regulator, fuel filter, battery, alternator, air filter, I have a new starter for when I do exhaust. Pretty sure I changed the air intake temp sensor under the plenum too not sure if that affects the car starting. EGR Deleted. ECM tuned with moates, VATS deleted with diode. Have not changed IAC, TPS, MAF, or MAF Relay. Checked all fuses. The car is running with no exhaust from the cat back. The only thing thats crossed my mind is the cat could be clogged or maybe the MAF relay took a dump because I dont hear the relay running that I used to hear when I connected my battery. The car will turn over and sound like its struggling to fire up. If I play with the throttle it stays on but as soon as I take my foot off it dies. After not starting it for a while car will run for maybe 30 seconds on its own before the idle drops and it turns off. Any ideas before I shove a broomstick in my cat or start throwing sensors at the car. Thanks guys