Just got truck back from dealer to verify numerous problems/codes. Dealer states previous owner has chip installed causing your codes. Strange thing is the PCM reads 40,000 miles and odometer reads 131,000.

Is it common to upgrade/tweek a factory PCM, say mabe sending your stock ECM in for a core and replacing with another? Could this be the case? I thought the PCM stores the VIN as well. Just sorta wondering why the 2 are reading different and how can a novice tell if there has been reprogramming or "chip" installed.

Truck runs great, gets 20 + MPG just has wierd idle issue sometimes and 4 or more codes stored. The dealer stated it may need a new PCM.