Stalling on a 1992 Honda Legend?

[AirJordan15]

I have a 1992 Honda Legend (Automatic) with around 120,000km on the clock, and every now and again it stalls. This happens when I am putting it into reverse/drive or when I am switching from reverse to drive or vice versa, for example during a three point turn or parking, i.e not while actually driving. I took it to a main Honda dealer and got a full service, but they could not identify the root of the problem. What should I try checking/changing and what are the possible causes of this?

Thanks in advance