LONG story ill try to be short. 496 bbc .585 hyd roller cam alum ported chevy heads edelbrock rpm air gap tko 600 9" 3.70 gear ran great with qf 850 carb. switched to fitech 800 mean street. new fuel tank w/400lph pump bypass regulator at 43psi. cant get it to lean out no matter what. back fire and popping randomly at idle, no power when I step on it. plugs (e3) carbon fouled. msd 6al2, hei, accel coil 13* initial 32 total. called fitech twice said I had emi trouble or exhaust leak. emi would show fault code, but no fault code. no exhaust leak. so both techs I talked to said "I don't know what else it could be, sorry" REALLY! I have read a ton of tech tips and tried A LOT of different things to try and lean it out. compression 180 in all 8. set and reset valves 5 times. pulled and checked all valvetrain no broken valve springs. no bent pushrods. all rockers in good shape. anybody got a guess why this is untuneably rich? Think I just made up a word. thanks.