1990 730 Stalls - but only until you select Drive

Any ideas . . . it doesn't matter if the engine is cold or warm, my 730 just will not go into drive without stalling - but only the first time! If I rev the engine quite high, shift into drive the car lurches and then is fine. I can subsequently select neutral and re-engage drive with no problem. If I switch the engine off and straight back on again the problem recurrs.

Any ideas please?

TIA