Good afternoon. I'm wondering if my throttle plate is the issue of a rough idle I'm having with my Mercruiser 350 MPI. Should the throttle plate be completely closed at idle? I have a slight gap when at idle. I assumed that the IAC handles all idle air flow. I've checked vacuum, all sensors, fuel, wiring harness and can't seem to chase it down. I'm down to either this or the ECM I think. Thanks!