96 Caravan Hot Start Problem

'96 3.3 runs fine, no problem at all when running. No problem to start from cold. But when it runs long enough to get the engine to full operating temperature on hot days and you shut down the engine, it will not re-start for up to an hour with the hood up to cool the engine, longer with the hood down. No problems except on days over 80deg.

Total lack of response for the duration of the problem, just a single click when you turn the key but no attempt at all to turn over. Then when the problem ends, the response is instant and strong and everything works just fine.

Anyone seen this before and can pippoint the problem?

Thanks.