Volvo Repair: 1991 940turbo wagon stalls when rains, distributer cap, heater control valve

Question
Hi Roger,
We have a 1991 volvo 940 turbo that sputters and runs terrible, if will start at all, whenever it rains or there is extreme humidity. We have changed wires,plugs,starter,etc. and can't seem to beat it. It will run fine when the weather dries out. We spray wd-40 on plugs,etc. when this happens and it will help it go, but still not run properly. Love this old car but not reliable in the rain. One mechanic siliconed the plugs to distributer cap to keep moisture out and that didn't work.Another issue we have is the heater doesn't blow hot air (it's luke warm) Help!! Thanks in advance for your response.
Sincerely,Kurt Barkdull

Answer
Kurt, I would start by replacing the impulse sensor on the bellhousing.    The running terrible may be a number of  things. Check all the rubber turbo hoses and see if there are any holes in them.  I HATE mechanics that try to fix cars with silicone.  It DOESNT work.  What brand of wires, etc did you use?  As far as the heater, I would check the heater control valve and see if its working properly.  Roger