A Little Help Please

I have a 1990 Plymouth Sundance, 67,000 miles. After about 5 miles of driving the car, it stalls! I can't always re start immediately, however, takes no more than 30 seconds to re start except in wet weather. Does not stall at high speeds, only between 5 and 40 MPH.This has been happening for about a 2 weeks now. Could it be the Hall Effect Sensor? Had a diognostic performed on the car. Nothing found!