Re: Getting a bit desperate...
I feel for you - once had a '85 BMW 635 with a similar problem - but only occured on wet or rainy days. I did not 2+2 together with the rain/puddles till several episodes occured. Turns out the previous owner had gerry-rigged a Mustang O2 sensor improperly waterproofed it and that caused the trouble. That stumped quite a few Dealers and BMW "specialists" and almost drove me crazy.