Ive been searching and I cannot find anything that is exactly related to my problem. I had a weak hpop and it would no longer start, so a T500 went in. started right up, but what I thought was a major hpop issue was the drop in rpms to around 500, then the truck would catch itself, and idle normal, on every tune. It started to get so bad that the truck would die when you left off the throttle and pushed the clutch in. Now, the truck is still doing it with the new icp sensor in. Is the drop in rpms IPR related? or does anybody have any ideas?