RichardJ,
Well spoken.
I was concerned he had the vacuum advance hose connected to full vacuum @ idle which someone stated that was the correct way to hook it up.
I think he needs to get that electric idle solinoid to work & that usually will kill the engine when the ignition key is turned off & really closes that throttle blade.
That should stop the dieseling.
He has a stick shift car/manual trans,500 RPM might be a bit low RPM for idle?
MBHD