intermittent issue.  while in gear, drive or reverse, engine will not rev while pressing the gas pedal.  shift into park or neutral, revs fine.  no lights on dash.  have noticed the issue affects temp as well.  if i shut the engine off and let it sit for around 15 minutes, starts right up and acts normal.  any ideas??

I would imagine there should be some fault codes stored either in the engine or transmission ECUs

Worth checking them out to see what comes up and work from there but definitely sounds sensor related