Car is a 1999.5 Golf TDI, GLS w/luxury package.
So I was driving in the rain for almost 3 hours today, at various speeds of around 60-130kph... And I noticed at certain speeds my wipers would move slower - slow enough that they would start skipping (staggering) their way up the windsheild, then a slow smooth stroke back down. At higher speeds and lower speeds they operated at a proper rate of strokes per minute... but not at around 90-110kph... Which is what I was driving when traffic was slower and the rain was the heaviest.
It seemed almost at random that the wipers would work "properly" again.
Could it be the (relatively new) wiper blades, or perhaps something is pushing them too tight against the windsheild... or does my car have speed sensitive wipers?