Problem with my 01, need advice

[HawaiianPSD]

Truck ran fine till this morning. Warmed her up for a few mins then hit the high idle for another few till the temp came up. Left work doing 15mph for a mile all good. Hit the highway and was good till 45-50mph then it started to run like ***, wouldn't rev to good, no power, just plain sluggish (oh yeah, engine light came on too). Pulled over and shut her down for a few seconds, fired her back up and the same thing. Switched tunes on my F5 and went back to stock to no avail. Was gonna have her towed but being 30+ miles up the mountain (expensive tow) I decided to limp her home. About 2 miles later the problem just went away and I was fine all the way home in any tune. Truck sat at home for 7 hours, I jumped in a few minutes ago and same problem, engine light on, idle kinda rough, sluggish. Left her sitting and used my lightning instead. Thinking it's the under valve cover harness (was suggested to me).

Anybody have any ideas whatz up? Truck has 125K miles. Thanks for any help guyz!!!

[Dixienormous]

exhaust pack pressure valve sounds like the culprit did you happen to notice a different tone in the exhaust?

[HawaiianPSD]

Didn't notice a change but... I'm running nitto mud grapplers and they hum big time so I may have not heard it if there was a different sound. What kind of tone would there be? What's the exhaust pack pressure valve, never heard of it. I know the exhaust bypass valve, have the decel tune on my F5 and know the sshhhhhhh sound when it's on.

[Dixienormous]

yea its a shhhhhh sound it "plugs" your exhaust right after your turbo its called a exhaust back pressure valve

[7.3eleanor]

Same thing happened to my 03. Got home checked the oil was 7 qts low. Filled it up prob. Solved.

[Dietoremain]

do the basics.. check the fuel bowl and make sure you have clean fuel and filter..

check your hpop and make sure you have enough oil and its not draining or not filling up.

check oil level?

UVCH could be the prob. but i would check a few other things before doing all that work to get the VC's off and look.

btw ICP sensor ok? unplug it and see if the truck runs normal..

[HawaiianPSD]

Thanks for the suggestions guyz!

[jthomas]

also check and see if there is oil in the icp sensor