Help Needed Rev up then dies, rough idle after warm up

[Goliath]

Im working on a friends 99.5 F350> When the truck is first cranked after being cool it runs great. But after it warms up it will idle up then the rpms will drop until it almost dies. It will do this the entire time it is running as it is left sitting. Also if I push the throttle and rev the engine then release it quickly the truck will completely die out and has to be restarted. It will restart without much trouble. The truck has about 150K on it, It is bone stock and was well maintained. It appeared to have the original CPS in it so I started there. The truck ran lots better and seemed to have back all the power it was missing. But after a drive to town and back when we pulled back into the drive it started the idling issue again. It now dies after idling it up again. It isnt throwing any codes and i checked the HPOP reservoir immediately after it dies and it has oil in it. My second thought was IPR. Is there any way to run a test to see if it could be the IPR? Any other ideas as to what it could be? The fact that it only does it after warmup is kind of throwing me off. But I know this truck is lacking power.

 

[Tail_Gunner]

I don't know of a specific test for the IPR unless you hook up to an analyzer. But there are some o-rings in there that go bad from time to time. A o-ring kit is available to rebuild the IPR. The worst thing about that task is trying to get it out. It takes a deep socket to do the job. I have a socket that is used for removing the axle shaft nut on a front wheel drive GM car. It worked for gettting the IPR out. BTW, be prepared for a flood of oil from the HPOP reservoir when removing the IPR.

Another thought, check the ICP connector. They have been know to get moisture in there (i.e. cleaning the engine off) and cause running issues. Pull the plug check for bent and/or corroded contacts or moisture. I put some di-electric grease in the connector plug and have never had an issue.

 

[Goliath]

where is the ICP connector located?

 

[Tail_Gunner]

where is the ICP connector located?

It's towards the front of the driver's side cyl. head. It's a sensor pointing straight up IIRC with a wire connector plugged into it. I don't think it's more than 6" from the HPOP reservoir or fuel filter.

I seem to recall a sticky post somewhere with a pic of the 7.3 with a lot of the components like the ICP labeled. I'm looking, haven't found it yet.

 

[skertin3rd]

Yeah so I just recently got the same exact problem with my 99 250. I changed the IDM, CPS, removed fuel from tank, blew out fuel lines, checked harnesses and installed locks on them, ran vaccum tests, pressure tests, removed fuel bowl and cleaned it, replaced the LL #8 injector, tested the HPOP and IPR. IT IS STILL DOING IT! I finally gave it to Ford and told them to find it. They say I am only running on 3 cylinders! 1, 7 & 8. I am going to replace all injector o-rings tomorrow and see if that helps. This is VERY frustrating.