91 transport stalls when warm
 

Hi all, I have a 91 Tarnsport 297,000 KM on it last weekend after driving for about an hour I stoped at a light the car shuddered and stalled. Started right up when I put in drive it stalled again, I can go to any gear (rev, neutral) and engine keeps running as soon as drive it stalls, if let vehicle cool down it works fine ??? looking for ideas where to start.

Thanks