Alright, i've tried everything I can think of before coming on here looking for advice. The car drives fine when you drive easily but when you lean on it, once it hits around 3k it (regardless of gear) it starts breaking up and backfiring. I can hear both fuel pumps on when I start (255 in tank, and 50 gph inline), I've fixed one vacuum leak and replaced a suspect vacuum line to the fuel canistor. Cleaned the mass air sensor and filter, replaced all plugs, plug wires, cap, rotor, fuel filter. Codes from computer are only 511 (it has a chip), 159 (80 mm Pro-M mass air meter). I've pulled the valve covers and looked for broken valve springs and found nothing, leakdown tests show little leakage coming from dipstick, compression tests cylinders are all within 5% of eachother. Only thing I can think is the distributor (MSD pro billet, been on since 2004) has some corrosion on it under the rotor, where the stator (or hall effect sensor......whatever it is) passes. I was thinking of getting a temperature gun or whatever it's called to shoot the headers and see if one is cooler than the rest. I'm lost....any thoughts.....
