Occassional high idle

[samiam]

The issue is that the idle doesn't always return to its normal level when I come to a stop. Happens warm or cold, but usually more when it's warm. For two years it has sunk back down to about 600 RPM, but lately it seems to want to stick about 900 whenever I come to a stop. If I drop it in to neutral it will lower down fast.
Any ideas?

[samiam]

Anyone have any ideas? My fuel efficiency has taken a dive in the past 6 months also. I replaced the fuel filter but it made no difference. My air cleaner looks ok but might need cleaned. Could air in the fuel line cause high idle? How about a transmission issue since the RPM's lower back down just fine when i put it in neutral at a stop, or when i pull over and park it?
in the mornings when it is warming up there's no issue. business as usual.

[ToMang07]

Almost sounds like a torque converter lockup issue.