My '89 560 SEL has started stalling randomly during the past 6 months. Happens at idle or at highway speeds. Hot or cold. Car will not restart until at least 1 or 2 minutes have passed. Then starts right away without hesitation. Very frustrating trying to prove it for the mechanic. However after much analysis, I noticed it stalled more during wet weather. Suspecting water in gas, I tried "dry gas" which sort of worked. Still had problems. One wet day it stalled 5 times on the way to work. I tried isopropyl alcohol as a gas line antifreeze and within 10 minutes no more stalls until the next wet day. Mechanic says there is no way I could be getting water into tank except with bad fuel. Since I use many different brands and stations, this does not seem to be the case. Could the fuel evaporator systems be letting in water when it pressurizes the tank? If so what is the best fix? If not where do I start next?
Thanks.