Took the car out today and it was running good. I jumped on it and banged a few gears. Very soon after it started backfiring and soon set the SES light. I check and it has maf high frequency, maf low frequency, engine misfire and also a CKP sensor code. Any help is greatly appreciated. I thought I almost had the car where I wanted it and now this came up. It feels like it drives normal then all of a sudden it 'coughs and gags' pretty hard. My #5 cyclinder shows alot of misfires also.

 

If I'm not mistaken the CKP code means crankshaft position variation not learned, correct me if I'm wrong. I also kept getting this code along with random misfire codes only after I had "PREDATOR" flash my computer for me. This happened to me a few times. I had to go to the Pontiac garage so that they could use their Tech2 for the relearn procedure, only takes a few minutes and it was done under warranty. Did you put a new pcm in your car or have it recently flashed. The problem with the CKP code is that it is a "hard code". On my car pulling the fuses or disconnecting the battery would not reset the pcm. The check engine light would only go out when the relearn provedure was done at the Pontiac garage. Sorry about the long reply but hope this helps.