If you have the COP stlye ignition, try replacing your coil boots. I just replaced mine and it helped the truck run better. They were 20 buck on Ebay.
Mine would run like crap after a engine bath. With the new boots and one new coil (#3) in place, I would like to spray the engine again to see if the boots really helped keep the water out of the plug holes.
I just closed out a whole forum under "coil advice" describing my isues.
BTW, mine would run crappy on wet days too, but only for about the first 5 miles.