I just got my '95 Buick Park Avenue. I bought it knowing that the power locks don't work. However, when it rains, the following things have happened:
1. power windows may stop working.
2. when pressing any electrical function, the lights dim and the engine stalls (only while out of "park" gear.
3. after car dries a little, everything is normal again.
4. The only repair I did was to fix the heat (replace thermostat, flush radiator and replace hoses).
moisture is the bigest problem,as for #2 on your post,sounds like the alt is not charging the battery.
one of your coil packs may have a unseeable crack in it, i have the ultra and we experienced this when driving in the rain, after a major tune up which included the coil packs and the "plate" under them (which is very expensive) i no longer had this problem
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