96 Z71 misfire????????????

I bought a 96? z71(5.7L) a month ago and it has a steady misfire in cylinder 2. I?ve scanned it and came up with a P302 code. It "chugs" at idle in gear and shakes a little at idle in park. I?ve replaced the plugs, wires, cap and rotor, fuel filter, put a k&n filter in it, had a new injector system put in it, not to mention having a stock exhaust put back on it. I am tired of paying for stuff that doesn?t fix the problem. The truck runs fine after acceleration, but a very pronounced shutter is heard in the exhaust. EGR valve, Compression problem, O2 valve? I?ve been told a million things and just want to get to the bottom of it!