[BCjetta]

I've had the Xterra back on the road for several weeks now (engine replacement). In the last week or so I've noticed it idling high when I put it in park and its warm. It idles high when I first start it cold but thats normal. Its generally idling around 1250-1500RPM in park when the engine is warm. If I put it in drive it goes down to 800 ish.

If its in park and at say 1250RPM and I give it a constant low amount of gas to get it just above 1500RPM then it will go up to 1500, stay there for a second and then go down to 800ish while I'm still giving it the same amount of gas. If I take my foot off the gas it jumps back up to 1250-1500.

Anyone have any ideas on this?
It also shudders every 5-15seconds as if its maybe misfiring or something when its at this high idle.

 

[zehn-x]

You can change the idle speed; there's an adjustment screw at the back of the engine (on?) the intake manifold. My Haynes manual has some instructions, but you can probably find them if you search this forum.

Before you do that though, you might want to get the codes read and verify there's not some other issue. If that gives you nothing, you might also want to check the timing with a light gun.