Some ECM are program to have high idle w/ engine cold in winter.
Many are high when first started and bump the gas pedal to slow some to a lot soon after starting.
Can check Engine Coolant Temp...
Get a ECM scan tool and read ECT report from ECM when engine is cold before starting. Plus Read/watch Weather or otherwise use local weather temp at minimum. Better, use IR or contact Temp to read engine.Why?
ECT sensor or wiring could be iffy making ECM to see colder engine then really is.
If ETC sensor is replace older then 87 then must get new plug w/ new sensor and solder the wires.
See my Cave, Scan Tool Help
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
The Ogre's Fiero Cave