2002 Ram Van 3500, 5.9 L, OD Auto.

Went to start van in morning. Had rained all night. Engine would not fire. Checked plugs, had good spark. Good pressure at fuel rail. When I let off key after cranking for a while, the engine would run backwards. Figured I had a timeing problem. I rotated the distributer clockwise about 20 deg. The engine started, but weak. It would not throttle up. After about one min. I moved the dist. back to where it was and everything was normal. I drove the van all day with no problem. The next morning after rain all night, I had the same problem.
Any help would be great, Thanks.[&:]

 

Your coil is weak or you've got moisture in the distributor cap. Pull it off and use a hairdryer to dry inside the cap and down in the distributor. If that doesn't solve it, then it's probably a weak coil.