Nissan Elgrand afs icon flashes.

I lost drive twice. One after driving 120km with a 1300kg caravan behind and once after 37km with the same caravan.
Both events were 3 months apart and normal driving of 400km per week in between.
The vehicle looses drive and once it's stopped, it revs over 2500rpm and hardly is able to move forward. Reverse seems to be normal.
After turning engine off for about 30 minutes, everything seems OK for a short while, then same problem again.
After first time, transmission shop drainer trans fluid and removed pan and checked for foreign matter and burnt oil. Everything looked OK. I added a 280mm x 190mm transmission cooler and bypassed the bottom of the radiator cooler.
AT light or engine check light don't illumi ate, just AFS off light??
I'm going to get computer log codes checked tomorrow.
Has anyone had a similar problem???
Manual shift mode seems to be disabled during the problem.