Yea man ..we way past that. This thing has SO many new parts. Im thinking its gonna end up being and electical problem. Possible Bad ground , possible Broken wire , or ECM issues? I'll update again when finally get this resolved ...so maybe it can help out another member. Thanks yall

 

I looked in thew shop book. Oddly, GM does not list P0303. They listed P0300, I added that info in a PDF. It steps through GM's diagnostics for troubleshooting a misfire.

Verifying the gap on the spark plugs as Nitehawk suggested is not a bad idea. If the gap is way off, weird things like this could happen. Even if they say they are pre-gapped, I always double check them.

Some other thoughts "out of the box", try using a inline spark light tester on the different cylinders. Reason for that, in one case I dealt with, a weak spark was determined with that tool. All the good cylinders lit the light bright, the problem ones lit it very little. Point of this exercise is to help isolate if this issue is a spark issue or is it fuel/air issue. If you can at least start ruling out potential problem areas, then hopefully you will find the system that is the cause.

Also, if you check the gap, check the condition of the plug. Is it wet with fuel or coolant or anything else unusual about it.

 

Was the MAF ever replaced?