runs rough over 750 rpm. idle ok

[goldenfalcon8]

95 F250 this eng, runs ok on first start up. When it warms up the eng.will start to run rough but the eng. will still run smooth at idle. shut eng. off wait 5 or 10 mins eng. will run ok for about 1/2 a mile then will start to do it all over again. anyone got any idea's Thanks
PS eng. has over 250,000 kms.on it fuel filter has been changed, glow plugs checked relay changed about 2months ago.

[pipelayerjdh]

Have you checked fuel pressure?

[overl0rd]

When was the oil last changed?

[sldghamr]

injector cleaner??

[goldenfalcon8]

Thanks guy's I'll try these ans. and let you know what happens. Just hope it's something simple as i am 325km from a dealership. Brian

[goldenfalcon8]

Thank you Changed the oil and eng runs ok. Eng did not have a lot of kms. on the last change but it had a lot of short trips this must be hard on the system. I am thinking i should use an hour meter. Any way thanks again overlOrd i appreciate your comments.

[overl0rd]

No problem. Failures on these are usually pretty minor problems, so it's always best to start small.

[goldenfalcon8]

Well eng. ran ok for a day after changing oil then started to act up again. A freind suggested checking the wiring harness so i so i pulled 3 plugs on the valve covers and checked them they looked ok eng ran perfect for a full day reved up over 3000rpm no misses then it started to miss over 750 again could it be a burnt or broken wire in the harness.

[pipelayerjdh]

Have you pulled any codes?

The valve cover harnesses are problematic.