1984 380SL Stalling

Help.
I have a 380 SL and it has been stalling a lot. I have a brother in law that had attempted to fix it, but it still doesn't work correctly. So far he has replaced the Idle Computer and the Idle Switch.

The car stalls at every other stop I do. I see and feel the engine going up and down when I go into a stop. Once I see the tachometer go up and down I know it will stall soon. I usually put into Neutral and try and rev the engine so it will release itself from revving on its own. Once it stalls I can start the enging pretty quickly.

The engine runs GREAT, just want to get it finally fixed.

Any clues will be greatly appreciated.

Thanks!

MadsG