Passenger side miss fire need help

[Jpro]

OK so truck is a 2008 Silverado 5.3l. Head gasket went and then was drove abit but not long and after that sat for a couple months before sitting at a buddies house to get rockers done. It ended up siting for about 6months and nothing got done so was brought home and sat in barn for another year. New engine installed But now seems to be running on driver side of engine intermittently and will then run on both sides. Have checked to make sure wires from ecu to coil plug have continuity have swapped coil packs around, has new plugs, wires, air filter, and fuel pump and fuel. Pretty much at a lost for what to do at this point. Any advice to help solve this issue would be great. 

[kamelred408]

 

do you have a scanner with misfire counter?

 

 

this harness going to the coils  check it / swap it and see if misfire follows

what are your fuel trims

what are your 02 readings

what is your fuel pressure

 

[Jpro]

Going to grab hp tuners and run some diagnostic on weekend last remember the only ode was p0300 but now went to look at it and basically not firing passenger side at all atm. Never though of actually checking that harness it's self. I am about to cut cat off and see if it's plug or not

[kamelred408]

i just unbolt the cat and thats what my problem was. im gonna geta  new cat asap