And maybe save an OBS truck from an arson fire!

Long winded but nessisary to get all the facts in, sorry

All summer long I have been fighting my 97 F-superduty one thing after another. Current brain teaser is a running problem that occurs only after it has set for at least a day but not every time it sits. Once it runs right it stays running right no matter if you leave it running or start stop operation. Here is what it does. When you start it it has a random but continuous miss. When I say random I mean different cylinders. When I say continuous it does not stop no matter how long you leave it run ( I have left it run 10 minutes that way). I have left it run that way long enough to heat the exhaust manifolds and every cylinder is firing tested by the manifold feeling test (not in Ford manual LOL) Now, you can shut it off and start it back up once or 20 times and it runs exactly the same BUT wait 2-3 minutes and try it and it will run on all 8 BUT then does not hold steady RPMs at Idle or if you press the throttle, best discribed by me as , romp romp romp ? Probably twice a second like you are mashing the throttle and letting off, no matter if at idle or take it all the way to RPM cut off point it does it shaking the truck violently. Now, you walk away from it looking for an ax, dynamite or paper to start a fire under it. Come back a half hour later it will start and run fine. I have been dealing with this for a month now and the above sequence is consistant.

What have I done so far in no exact order done
1 Put my OTC scanner on it. No codes.
2. Watched the data stream and while I dont remember the numbers and percentages none were out of line as checked by a decent Ford tech. ICP % and HP oil pressure stay steady when engine is romping.
3. Ran buzz cold test- passes every time
4. Ran all other tests including contribution, all pass. tried to run contribution when cold and not running right but it wont run until oil is hot.
5. Borrowed ECM and IDM from another truck, no changes.
6. unplugged ICP no change in missing or romping but truck barely runs.
7. checked fuel pressure at all satges of running good or not 70 Lbs
8. Replaced ICP with known good
9. Checked fuel bowl after sitting- full
10. Checked HPOP res after sitting- full
11. Wiggled and jiggled every harness while running right or not, no change
12. removed and cleaned all grounds.
13 Injectors (Rosewood), valve cover harness (ford) new in last 3000 miles.
14. changed oil
15. replaced IPR with known good and new O-rings (nice to have a buddy with truck)
16. Pulled T-S chip out, first thing I did.
17. fuel filter
Anybody care to take a stab at what I should do next? I kinda need the truck.

 

WHATS THE FUEL LINE PRESSURE?
ALSO CHECK HOW IT RUNS WITH THE MAP UNPLUGGED
THEN UNPLUG THE EGPR THEN CHECK IT
THEN RUN CODES
IF NO CODES YOUR SCANNER IS NOT READING
IF THE AIRVENT/RETRN SCREEN ISNOT FOULED OUT THEN MY WAG IS THE UVCWH OR BARO SENSOR UNDER DASH BY YOUR LEFT KNEE

 

Look close at the IPR wires and that whole section of harness. Take it out of the truck and pull the loom off and look over every square in ch to make sure it's not deteriorated anywhere.

Is this the truck with the SRP1?

 

Thanks, sorry I should have clarified that it doesn't read codes when I havent done something to make it read one. Yes it trips codes when I changed the computers and unpluggd the ICP and other sensors while running.