My 99 Disco 1 SD idles high when I warm it up in the morning. The tach runs up around 2k until I put it in drive and it idles back to normal. Any ideas? I've never messed with the idle switch or anything like that.

 

How long does it stay idling like that? Mine idles high but only for about 10 seconds, then goes down to normal. I religiously wait those 10 seconds before I engage in D or R every time.

 

It idles high for several minutes, as much as 10 min, in the morning until I get in and put it in drive and it settles down. It's very strange, I've never had a vehicle just idle so high on warmup. It's the nature of fuel injected vehicles to start at a fast idle for a few seconds and settle in to a normal idle, but my Disco idles too high for too long. I just wondered if there was an idle sensor or something.

 

http://www.roverparts.com/Parts/ERR4352.cfm
Look for this on your throttle body, remove it, clean it with a can of carb cleaner, clean the hole that it goes into also, put it back together and then see what happens.
That controls your idle speed when cold.

 

Thanks spike, I'll try that and let you know.

 

Also, keep an eye open for a vacuum leak.
Normal idle should be around 1200 RPM's then dropping down to the low 700's.