Well I ran a cylinder contribution test on my truck, using the scan gauge. last time I ran one was probably 2 weeks ago and it came up clear. today i got the following codes, p0263 p0269 p0272 p0284 which is cylinders 1, 3, 4, 8. Haven't noticed the truck running differently than otherwise. I just put my new chip in the other day, other than that I haven't made any changes. Also, I randomly got a p0344 code which is CMP Sensor Circuit Intermittent. I recently changed the CPS, used one of the crap advance auto ones just for a temp fix. could it be that the CPS is starting to fail and causing the cylinder contribution codes?