I have a 1996 f250 4x4 with a 7.3. I have replaced the low pressure melling pump, the high pressure pump, fuel pump, fpr spring, ipr, icp and both undervalve cover harness and all four pig tails and my idle in park is erratic you can feel it in the truck. I can put it in gear and it stops. What do I need to look for now? Please help as this is driving me crazy

 

have you driven it 100 miles after doing all of that work?


are you sure there is no air in the fuel?


is fuel pressure at least 45 PSI during a WOT run in third?


clean FPR Screen?


possible you have a bad injector, can you do a buzz test and CCT?

 

I've done all of those things, the buzz test and cct come back good no faults no check engine light. I'm a diesel mechanic by trade and this has got me stumped.

 

have you tried to unplug an injector one at a time to see if only one is misfiring?


Does it run rough in neutral as well?

 

Yes I have unplugged them one at a time and all are working, Ill check and see if it idles fine in neutral. Should I start it in neutral or in park to check it? If it idles fine in neutral you think the trs is going out?

 

TRS might need adjustment if it idles ok in N


Don't matter where you start it

 

How do you adjust it? I thought it was preset at the factory.

 

my bad, I was thinking of the one I replaced on a chevy this winter


does it idle better in N?

 

I haven't checked it yet I will let you know in about 20 minutes or so.

 

Isles the same in neutral as it does in park.

 

Have you tried STARTING it in neutral?

 

Yes does the same thing