If the soloniod on the IPR is working, Then the IPR valve is probably stuck. If you want to remove that variable, get a new one. I see them on E Bay for cheap.70 -100 dollars sometimes.....
Found a couple on ebay, cheapest one was 150. Not for sure if the solenoid is working or not, haven't really had a chance to look at it to hard. Still haven't even towed it home. Was it the IPR that was giving your truck problems?