What will cause my van to miss when you accelerate and smooth back out when you let off acceleration?

What is your question?

It had came a big rain and during this time I got gas at the local Marathon Ever since then my van has started missing and going on. One min it will run fine . Then the next when you go to accelerate it starts missing and cutts out. Then when you let off the acceleration it straightens out. What is the problem?

What makes this problem better or worse?

When you give it gas it gets worse and when you let off it straightens out.

How long has your 2006 Ford Freestar had this problem?

A few days