High Idle

[bh357]

In the correct forum this time I have a 2003 GT with a bit over 160k miles. Lately the rpms haven't been dropping all the way when I let off the gas to slow down. It'll drop to just under 2000 rpm. However, if I give the throttle a blip with the clutch engaged, the rpms will drop down to normal, and it'll idle that way just fine. No blip of the throttle, and it'll want to idle at the higher speed.The only DTC I've had is an occasional 420 code, which has been ongoing for a very long time. The idle issue just cropped up a couple weeks ago. There are no other driveability issues.

[joatmon]

I looked in the matrix repair manual and for high idle it says the causes could beidle speed control (ISC) valve circuit problems-PCV hose-Open or short in ISC valve circuit-ISC valve is stuck or closed-Open or short in A/C switch circuit-Air induction system-ECMor - ECM power source circuit- Neutral start switch circuit (AT only)- Back up power source circuit

[RIT]

Sounds like the throttle cable is sticking, and may need to me lubricated. If it were an electronic problem, then blipping the throttle would probably have no effest, so it must be mechanical. i suppose the IACV could be sticking, but i would start with the throttle cable.WD40 is your friend. Or maybe some Gumout on the cable 1st to remove some grease/dirt that may have built up on it.