Hi,

New user here, like the looks of the community so far.

I'm having an issue with my truck, seems if I'm real soft on the throttle the truck runs ok, but step on it and it starts to shudder and misfire around 60-80 km/h (50-65 mph).

Initially it seemed the problem was with the manifold back-pressure tube being clogged. Had that cleaned along with the back-pressure sensor valve, the truck seemed to run better. Within 48 hours the same problem returned. A code scan indicated the back-pressure sensor valve was the culprit, replaced, but did not cure the issue. Subsequent scans pointed to the same sensor and the corresponding circuit. We deduced it was the IDM, which my mechanic confirmed by swapping it out for an older one he had on hand. I picked up an IDM from a wrecker, and the truck seemed to run fine until 72 hours after the fix.

Now the truck behaves as described in the first paragraph. Ambient temperatures don't seem to be a factor, just load. I had some thoughts, but I am hoping to find someone that has seen or experienced this before.

Any help or thoughts are greatly appreciated.

Thanks

Jak