Jeff,

One other thing to consider is that you might have a bad ignition switch.
These are easy to install and cost around $10 at Vanagain.com.  Next time it
won't turn over, try wiggling the key in the switch while cranking.  Or, if
it starts right up you can try wiggling the key to see if you can cause the
engine to cut out.  I had a problem with a couple of our VWs not cranking
that turned out to be a worn ignition switch.

I don't know how this would relate to your loss of power or shifting troubles
though.

Roger