Engine stalls occasionally at idle when in gear, otherwise runs perfect. Vacuum?

Thanks for the response. Idle seems a little high and cruise loses a little speed going up a hill. Also the "Service Engine Soon" light came on today. Stopped by AutoZone to read the codes but found none. Light was off when engine was restarted. Since it has been driven less than 1000 miles in the past year, I sprayed some injector/carb cleaner into the throttle body (TBI fuel system) and will take it on a more extensive drive later.