Thanks for suggestion Leroy but the Cyclone engine in my car has an electronically operated (FBW) throttle so no need for an IACV. Idle never fluctuated from 750 rpm norm once warm anyway.
As an aside I have swapped ECU relay for a spare and checked and reseated all engine fuses. I also put in my Bluetooth OBD2 adapter and used the Torque app on my phone to check for stored fault codes - none found. I did notice whilst ignition on but not engine that the throttle position display was set at approx 17%. I'm guessing this is a cold start position. Pushing pedal moved it through the range on dial display and you could hear the actual stepper motor operating which seems normal.
Frustrating thing is I now need to drive for maybe a couple of thousand miles to prove I've fixed issue (or it's fixed itself
)
Thanks for your suggestion too Heinz but engine and general conditions were dry. On each occasion it happened car had run fine for 20 miles or more. Have checked MAF sensor plug and have cleaned it in the past but it was spotless.
