Truck has been running fine. Went to start the truck, starts up fine but runs rough and low on power. Only code is p2290. Icp at idle is 560-570. Truck starts up no problem. Ipr at idle fluctuates 21-26. I revved it and it hit 86 on the ipr. I replaced everything in the hpop system last winter. I have a feeling its the ipr valve sticking. Its an alliant power ipr. Icp readings are good. Swapped the icp out for a low mileage one I had on the shelf with no change. starts up fine hot or cold just runs rough and not full power.

 

I'm not a parts swapper by default, but I would pull the IPR and check the screen on it and the seals.

There is a tool that you can manually control the IPR valve with for air testing so in theory there's a way to bench test the valve if you remove it, but I do not know what the correct values would be.