Thanks for the post. I've been fighting with this problem for about a year now. Replaced both front ABS speed sensors, the MAF, and some other bits local Porsche mechanic suggested. It turned out to be the $20 switch all along. 5 minute install and it's working like a champ now.
Here's a picture of the package and the old part. The only tricky part of the install is access to twist the new part in if you have big hands. It's not very difficult though.
