help me this car is driving me nuts

i have a problem i have a 2000 3.8l camaro i have replaced the 02 sensor, cleaned the maf, put in 2 new icm, replaced 1 coil and i still get a misfire. it will missfire on the number 6&3 so i thought it might be a coil but i tried swaping them and same thing then i tried a new icm same thing then i tried new plugs and wires same thing. I am about to pull my hair out i unhook the injectors and check while it is running to verify and the number 6 and 3 give me no diff in rpm while the rest yoiu can clearly hear a diff. every so often they will start working again but week and then the cylkenders go right back out i just can figure it out.

ok so i take it to auto zone and have it scanned again and it came up it was running to rich on bank 1&2 plus the random missfire so i unplugged the maf and it ran better on all cylanders i then went to the scrap yard and pulled a maf off a another car not sure the size of the engine but it looked the same i know it was not a 3.8 car runs better but has a loss of power does it matter what engin the sensor comes of or are they all the same