[JP Noonan]

Advancing the timing that much (assuming that it was close to spec to begin with) can blow up the motor from detonation. Advancing the spark does give VW's a lot more power but even without detonation it overheats the motor. Also in your case it is a band-aid fix.

Use a vacuum pump (Mity-Vac sold at FLAPS) and test to see if the vac advance/retard diaphram is working. As you apply vacuum the points plate should move, if not make sure the plate isn't seized, if it is free the vac can is bad. I had one go bad, wouldn't hold any vacuum, and causes all kinds of probems.

Another problem I've had is the advance weights sticking from rust. Usally this means either no advance if they are really stuck, or the advance comes on all of a sudden, and then won't go back down, neither will the idle.

There are also two little springs in the distributor that control the advance weights, they can rust and break off, this throws off the advance curve, or the advance is on all the time. Found a '72 with one spring broken, but the rest of the dizzy was in bad shape too.

Besides the vac can all the parts I talk about above are under the points plate. So unless you take the plate off it is hard to inspect. You can take the FI points out of the bottom of the distributor and look for rust or parts to the springs.

Don't ask how I know, but check out that the vac lines from the throttle body to the dizzy are correct. There is a diagram somewhere on this site.

Look at the timing and dwell article then set them to spec. Check the spark plugs to see if it a problem with all the cylinders or if just one looks a lot different from the rest.