89 Caravan Turbo..no start. help, please?

My 89 Dodge Caravan has developed a split personality. It runs really well most of the time, but whenever we get a good rain, it won't start for several days. It's actually not starting at all right now from the rain 3 days ago. I checked and replaced all the normal things. New wires, plugs, cap, and rotor. Checked the cap for moisture, sprayed it out with some wire dry and wiped it off, thinking maybe the somewhat shoddy cap design was at fault, no luck. I checked for spark at the coil wire, nice defined blue spark. On the other hand, there is no spark at the plugs. On the occasions where it did start after a couple of days of sitting, it would run really rough for a minute or two, missing, a bit of smoke, etc, and then would smooth out. No problems with cold morning starts, just wet. any ideas? I'm at a loss here.

If you have good spark at the coil, then you have a problem at the rotor and the cap. First, make sure the rotor is turning. Then check to make sure the inside of the cap has the carbon contact and moves up and down and makes good contact with the rotor.
Good Luck.

the rotor is turning, the cap is brand new, as is the rotor. i'm at a complete loss here. went down today and the van started right up...yesterday it turned and turned, to the point of wearing down the batttery a bit and nothing. it tried to fire once yesterday, but the battery had started to drain a bit, so there wasn't enough juice to keep the engine cranking quickly.

I have the same problem.

replace the distributor pickup (hall effect). It's about $40 and will give these symptoms.

Slantsixness