Howdy, at first I'll post a disclaimer that I have no experience with these cars, just bought a 97 850 myself and thought I'd stop by the forum.. Now, about your issues with hard starting/running in damp conditions - it could be your distributor cap is cracked and is allowing moisture in.. That would be my first guess anyways as it was a common problem on my old vehicle, a GMC Jimmy.. Hope that helps..
Ben