Hi Robert here's something I found that could help.???
2005 Jaguar X-Type 2.0d - Jaguar diesel idling high, especially when driving - My Jag has a frustrating and dangerous problem. The idle speed increases when the car is in motion, getting up to 1500 rpm - which when in 5th means acceleration with no input from me! With the cluth depressed it drops to about 1000, and when the car actually is stopped returns to the correct 800 (with occassional surging) I have had the local garage hook it up to diagnostics but the car is clean with no codes at all. I cleaned the EGR valve myself and that made no difference. I would say the problem is worsening. Could this be a sensor? ------------------------------------------------------------------------------ Answer== Check your engine oil level isn't above the high mark. If ok, I would check the turbo oil seals arn't passing excessive oil. owner Unplugged the MAF last night - no change : Answer== Does that not tell you something.It could be that the MAF is faulty or that the wiring to it or the plug is faulty all three common problems on this engine.Having a faulty non operative MAF will give exactly the problems you describe.
Then have a look at this????
http://www.oilem.com/tag/maf-sensor-cleaner/