the other night my car started misfiring pretty bad out of nowhere ( and it started to backfire out of nowhere) and I was driving normal, I got the flashing ses light.....so next morning I bring it to my shop and scan it there is no codes and everything seems to be working fine but it is still misfiring, so My friend (a tech) tells me to disconnect the maf and all the misfires stop, but I think because when this happens the pcm disregards if there are any misfires...But then I clear code for maf and everything and it starts showing misfires again on the scanner, however it is not as bad as it was, and it isn't popping anymore.... however it shows that just about all cylinders are misfiring but number 4 is the most active of them all, so we check ignition and it's all good, spark and everything, I pull plug #2 & 4 and they are both perfect looking and I swap them and #4 is still the worst.....
So I check fuel pressure and a volume test and it's good, I pull injector#2 & 4
and they're both clean and have good resistance, and swap them anyways, and cyl 4 is still the worst. vacuum is good and steady, I tried to reset the pcm by disconnecting - terminal, and still I haven't found anything and I am still getting multiple misfires, however the ses light is not blinking

Please let me know if there is anyelse I could check to see that is messed up, If anything I am trying to find an ls1 specialist around nyc that will be able to help me out here, the car was done by vette doctors, so I was thinking of going back to them but just wanted to search around before I did anything
I also put stock maf in and it made no difference
the car has a thunder racing 224/224 cam, kooks lt headers and y pipe with high flow cats,ram air kit and cai, borla exhaust, granetelli maf, ported throttle body, ls6 intake manifold