Auto box , stalling

This is a weird one.92 g-wagon lwb 463

3 litre engine with auto box.

Stalls, usually at 5-15 mph,sometimes 4 or 5 times a day. other times, not for a week or two. Starting process is turn off ignition. then turn on for about 10 seconds without cranking then repeat once more.Then it always starts again. Whats that all about then ???