Cut

I checked code again and it is P0237.

I get an over boost code periodically sometimes accompanied with a cam position sensor code sending truck into limp mode. I can erase codes and may come back the next day or sometimes not come back for a couple of months. It's a 2001 2500 5spd 4wd it has a edge comp box, fass fuel pump, injectors, slightly larger turbo, it has 135k miles on the truck. Any idea where to start?