1998 Dodge Caravan kills while driving

I'm having a strange problem with my 1998 Dodge Caravan (3.3L/V6) that has 98,000 miles.

The problem started last winter. I could start my van just fine, however after I drove for 15-20 minutes and would come to a stop, the engine would kill. I could start it up again, but when I come to the next stop it would die again.

I took it to a couple of mechanics. One replaced the fuel pump and another replaced the serpentine belt.

I had no problems from March through November, then as soon as it got cold outside, my problem came back.

Please help!