[BennyBall]

Start by cleaning the throttle body butterfly plate with carburettor cleaner and a toothbrush, they can gum up badly with hardened carbon deposits and cause the throttle to stick, do the same with the idle control stepper motor, see if this helps, at least it will cost almost nothing!

Benny.

 

[BennyBall]

When the engine is running, try the "wiggle test" on the wiring plug connector, trying to replicate the fault, while the car is stationary. The pins on these plugs are thin and fragile and can give intermittent contact. Work the plug in and out of its attachment socket several times, electrical spray contact cleaner can help here, if you get a better result, sometimes splaying the pins slightly, and carefully with a small screwdriver can establish a better contact.

That throttle butterfly and the surrounding aperture MUST be spotlessly clean, a quick wipe over won't do, I fixed a Ford Focus with similar problems just by laborious cleaning here........see if this works.

Benny.