Bongo Fury

This received from member Rob from Wiltshire. He has a diesel automatic.

Odd one this morning, started OK, reversed, then when put into drive revs dropped and kept cutting out. Eventually got the revs up and seemed to run OK when driven around the block. No warning light, no unusual noises. Any ideas? 2.5 diesel.

*UPDATE*

Started this morning, same problem but really made mechanical rattling when put into gear before cutting out. Warmed engine, checked ATF fluid, all fine. BUT when I put it into drive or reverse this time when engine's hot, theres no problem.!!!! HELP!!

Hopefully someone can help?

Rather similar sounding problems to the ones I had back in August 2018 which resulted in a gearbox rebuild.
I didn't get a descriptive report from the re-builders, just a big bill, but something metallic appeared to break off in the torque convertor and cause chaos for about 3-4 miles and then it seemed to run OK (sort of, odd noises), but at the time it was obvious that something very bad had happened inside the gearbox and that there was going to be a lot of shrapnel and grindings floating about inside the oil. My normal garage wouldn't touch the gearbox internally but they arranged to get it to a local gearbox service place (run by a person who had a a Bongo and is a member of the forum) took several weeks to sort out but after rebuild it worked fine and is still running perfectly to this day with the gearbox.
I opted for the rebuild, and bill, rather than simply swapping for a second-hand gearbox simply because I would have a guarantee on the work and parts as opposed to a totally unknown gearbox with unknown history which might have failed in a similar manner whilst out touring!
Good luck!