Thanks for suggestions but 3.7 V6 uses coilpacks. Will leave as is now after ECU relay swap, re-seating fuses, cleaning MAF sensor and re-seating throttle pedal connector. Issue seems to be a very intermittent minor one and resets after engine stop/start. Might take it for a run with OBD2 connected to phone and see if anything shows up.
So far have found throttle position starting cold at 17% and dropping within a few seconds after engine start to 14% whilst idling at 800 rpm. Probably lower at idle with fully warmed engine. Full pedal reads exactly 75% engine off so guessing this is an PCM coded setting.
