'94 Z28 A4 w/ 110k. Intake, headers, exhaust. You know, its usually the "No shift" problem at WOT, and I had that. But now as I widdle away the trouble spots, more seem to appear. Car has a new opti, and waterpump, and recently had 3.73s put in. Car runs amazing, best it ever has during daily driving. Want to give it 80% throttle? Sure, it runs great.

HOWEVER

If you want to mash it to the floor, either from a stop or while cruising on the highway, it kicks into high gear and does nothing but backfire, slowly creeping up the RPMs (momentarily throwing a code) until you let off the gas slightly, causing it to come back to life. SOMETHING about commanding WOT is seriously throwing something off. I checked codes and got 32 for EGR and a subsequent rich code which would explain the backfiring...right? I'm going to remove the EGR shortly, but is this consistent with a bad coil or fuel filter? It doesn't happen at any "specific" RPM, its pretty simple. If you mash the pedal to the floor, it will backfire when it downshifts into high gear, no questions asked.

Help.

 

Its a bad o2 and fuel pump.