Trouble restarting after warmed up

What is your question?

My 1999 volvo s80 2.9L non turbo has trouble restarting after warming up. When it does run it runs great. I was told it may be the engine coolant temperature sensor... ?

What makes this problem better or worse?

Starts fine after engine sits and cools

How long has your 1999 Volvo S80 had this problem?

The entire three weeks ive owned it