Car running lean, any suggestions?

[MATTKNIGHT]

Okay, guys, I will start by saying sorry if this is long winded. I want to give an accurante account as to whats going on. I have a 95 gt, 72000 miles. I installed long tubes, off road h pipe, flows, cold air, msd 6al, new distributer (oem replace), msd coil and i think thats ablout it. I ecountered a problem a few months ago when my car started running lean. I checked my fuel press- 36psi @ idle. I replaced my o2 sensors hoping it would help, to no avail. I replaced my fuel filter and got nothing. I cannot figure out what the prob is. I checked every chilton/haynes type manual for help and got nothing. I am kicking a soft fail check eng light. It comes on during heavy accel. Downloaded the fault and got "left bank running lean" and "right bank running lean" as well as an "egr" code. The only modification that was not a direct bolt on was the headers. Everyone knows how they interfere with the smog lines in the pass side eng bay. I reset the comp numerous time as well as checked and reset the timing at least 7 times. Please help me, my car lost so much power in the 3800 - 4500. There is a signifigant loss in power throughout my rpm range as well. My great running car is giving me a headache. I got beat by a Honda the other week. I need help...