Ok I have owned this unit since new, GM has replaced the ip several times, just replaced the fuel lines(porous), lift pump and fuel filter. PMD is remotely mounted on a heat sink, the unit will not idle....it surges from 1k to 22k continuously. P1216 code in the history. any help would be greatly appreciated, treated the fuel with booster and cleaner.

How long have you had the PMD remote mounted, and where is it locate? Since your pump has been replaced a couple of times, is there still a PMD on it, and is it still good? Or if you have another known good PMD, I'd try that and see if the symptoms persist.

Don.