So I have a 99 454 k2500 sub. It has a misfire on 2 and 3. I have done the normal tune up things. Its been doing this for a while but has got worse. Already replaced injectors, FPR, Filter, Pump. Just did intake gaskets they were leaking. And yes it was like this before. Compression is good. 150 to 160 on all cyl. When doing the gaskets found 2 bad lifters. Replaced all. Replaced cap and rotor the rotor was worn. Fuel pressure is 50 KOEF and running its at 55 and if I rev it it may hit 60. Fuel pressure seems low to me that's why I put in a new pump Its an ac delco. I'm at a lose can not figure this out. I'm using hp tuners to do data logs so if anyone has that I can post a file.