Temperature sensor ? Although that's usually related to difficulty starting when warm and running too rich iirc.
Originally Posted by tabetha
see what the idle does, set it to 850 rpm, with HOT engine and NO LOAD
The correct procedure for doing this is to use the idle screw which is just under the front of the throttle body (easiest to get to if you remove the hose between intercooler and throttle body.
Do not (as I have done in the past), use the adjuster on the throttle cable to set your idle
PS: There is a high likelyhood that the screw will be jammed solid and may need a little persuasion before you can turn it (old cars for you).
Good luck.