[taxman82]

Sounds simular to a problem I had with my 99 silverado (new body style). It was some body filler missing from the upper door frame. It is easy to see if you open the passanger door and pull back the black rubber trim. You will see a seam that should be completely filled with filler, mine had a hole about the size of the head of a pin that when it would rain would soak my passanger side floor. You can also do the water test with the inside trim piece (by the windsheild off, it just pops off) if this is the problem and you spray at the door or top of the windsheild you can see it run down the inside frame. Also check the blower motor area, there is a sponge (for noise reduction) that will get soaked and cause the blower motor to go out.
Finally, my truck also leaked from the door itself. If you spray water on the window of the passanger side door, I had water coming out from just under the pocket in the door, seamed to get in behind the plastic barrier. Never did figure that one out got rid if that POS first. Have a suburban now! Might be worth a look and sorry for the length.