2004 XJ8. Recently had the fuel pump and transmission pan replaced. Since then I notice that the idle speed hangs up a little. When I come to a stop the idle speed is about 1000 rpm and the gradually drops over about 10 seconds to about 600, previously it would drop immediately. Could this be a throttle body problem. Thanks for any insight.

 

I supose you could be right-it's an 'old' car now (like mine) and the throttle body could need cleaning.
No harm in cleaning it in case it solves the problem but only use the right cleaner for the job.
I believe that there is a coating on the inside which should not be removed although I can't imagine why it should have this coating.

Look for this excellent write up with pictures! on the internet
Cleaning the Jaguar XK8/XKR Throttle Body, MAFS, and Part-Load Breather

 

Thanks Merion1 - for some strange reason it has suddenly corrected itself, however I think I will go ahead and clean it anyway as in my experience these kinds of issues tend to return; any idea what kind of cleaner?

 

This could be completely normal.This also happens if you change you sparkplugs and which makes the engine run easier then the idle speed goes up until car has readjusted the speed which can take some time. Be careful not to force the throttle body open when you are cleaning this can destroy some cars throttle body.

 

Thanks MTW, never thought about all those computers taking care of me! Maybe I'll just leave well alone and see what happens.