My 97 SD has had this same miss since I got it back in the fall. Testing in the fall said it needed #2 and 8 injectors which I replaced. Truck ran differant but still has miss. Truck starts easy, no smoke runs well until hot then developes am miss. Runs fine on level ground and pulls great but go down a hill and when you level out or start back up and need some power again it will miss, dead miss on one cylinder. If you mash the pedal it will never come out of it but if you ease into it it will miss for a second or two and then come out of it sometimes popping out the exhaust when it starts to hit. Will also miss if you stop at a light, not sitting at the light but when you accelerate away from it, again only when hot. Well we got it back on a scanner again today while hot. (the truck passes the cold buzzer test) He ran the test while running, "contribution?" I think? First time said number 1 and 3 injectors. He ran it again just for kicks and it said Number 2, ran it again and said 2-8 (the ones replaced in the fall. He probaly ran the test 5-6 times and each time iot gave differant injectors as bad other than I dont recall #7 3 or 5 being singled out. The elecitrics ohm out fime and evrything in the wiring looks OK nothing burned or corroded. The mech is lost and so am I but it took little to loose me, LOL He has checked the HPOP and says it OK.

Care to take a stab?

 

So it doesn't miss cold? If that is the case there is either a HP oil issue or an injector issue. Could be injector o-rings but more than likely and internal injector issue where it is bypassing oil. You can pull the VC's and start the truck and watch for oil flow steady out of the oil spounts and also watch for spurts of oil where the injector goes into the head.

 

I agree with TJ...HPO system or a sticky IPR valve.
Do you have a stick or auto trans?
I copied this from dieselmanns web page:
PowerStroke Diagnosis

 

Thanks guys, Yes the truck runs perfectly when cold and warming up, only after it is hot does the problem show up. It is a 5 speed. What has my tech scratching his head is the tester keeps showing different injectors. His own truck has a known bad injector so he hooked it up just to check his tester and it works fine on his truck. HPOP is kinda high buck part for my way of "diagnosis" which is "guess and replace" We will pull the covers again and check what you suggested.

 

X2 Tj/Cuda

With the failures being random what is in common is oil and fuel.
I would test drive with the scan to see IPR and ICP. Also remember that what the scan shows may not be true. Best is with a gauge on the oil system.
On the fuel side check pressure and for air in the system.

While you have the VC's off pull the coils and check poppet air gap.
You want to see .002

Bill