Question about Starting

Well the idle thing is just the computer goin from closed to open loop operation (or is it the other way around). Anyways its just the computer trying to get the motor warmed up so the thermactor system is directed towards the heads and more fuel is being thrown in. Once warmed up the thermactor system goes to the cats. So thats why the idle is high then drops down after a few secs.

The dieseling can be a few things. Carbon buildup in the cylinders, too much fuel pressure, or fuel lines getting too hot. My car used to do that until i lowered the fuel pressure.