I recently disconnected the battery for access to a fallen item and have been so far pleased that after noticing the engine relearn the idle revs this puzzling business of the engine wallowing below the warmed up idle revs of ~750 RPM to temporarily a somewhat shaky 500 when finishing a downshift out of 3rd, seems to have been resolved.I am going to make a point to do this disconnect twice a year since maybe the ECU can detect winter/summer gas (not suspected in above snag) to run more efficiently.Maybe some volks would like to add some benefits they've observed from doing a reset.
I've done it like 4 times. Not to reset it, but to reset the radio. Mine likes to have a hiccup and forget how to spell anything like the words "VOLUME" or "EJECTING DISC" or "LOADING..." so I have to disconnect the batter instead of pulling the radio out every time. OH, and I've noticed NOTHING.
I've done this after I clean my MAF sensor. It actually idles at a scary-low 400-500 RPM or so, giving the car a hell of a shudder (only when at stop lights) for about 20 minutes of driving. Then, it's smooth-sailing again once it learns my habits. I quite honestly don't see a whole lot of difference since I have been keeping up with my MAF cleanings. The first one helped a lot because I think I over-oiled my K&N drop-in air filter.