Same problem. except the one fine day in a downpour on the interstate, the wipers (on med setting) quit altogether. waited for it to clear, came home and tried to figure out the issue. first thing, I noticed on removing the wiper motor is that the spindle still moved when stalk switch was in high setting so the motor looks good. No movement though on intermittent. secondly, looked at the link assly and the small white thingy which sits on the shaft bulbous end and connects to the link assly was not in place. (any idea what;s it called and can I buy just that rather than the complete link assly ?)
all that done, looked to me that the stalk switch is faulty? any idea how easy is to DIY?