pumpkin plants dying?
Answers:
If the leaves were wilting quickly (and if they came back temporarily with watering), I would think the problem is squash vine borer. But that is not what you are describing.
I think it is either an overwatering or underwatering problem.
Other answers:
too much water? possible root rot
too much water? possible root rot
TAKE A LEAF TO A GARDEN CENTER BEFORE IT'S TOO LATE!