Hey guys, I'm having issues with a high idle with my 04 SD, I changed the air idle sensor and still have issues. It has a 6 speed manual and when I come to a complete stop it idles down to normal as long as I have the clutch out and in neutral. If I have the clutch pressed in, in gear, or slightly moving, it idles around 2500 rpm. Any ideas are gratefully welcomed.

 

Maybe yes and maybe no,
Think about and look for what changes when you depress the clutch pedal.
Sometimes a poor ground connection between the engine component ground and other grounds gets moved or changes due to unseen corrosion .
Something you can try is to insure the ground for the computer is not the problem by just installing another ground wire from the battery negative post to the sheet metal and a few other grounds. It's quick and doesn't require any special tools other than some 14 gauge wire and cleaning where you secure it. Your vehicle may already have a separate ground from the negative battery terminal to the sheet metal. Some take the ground from the engine and use that. You would need to know where that connection is on the engine and check that connection, usually somewhere on the top of the engine.