I have a 1995 E300D that has intermittent electrical problems which
seem to be related to my ignition switch.  Usually the problems occur
after the car has been parked in the hot sun. Most common problem is
that the radio looses power, it keeps coming on and off especially at
low RPM.  Once I lost all dash lights, then the next morning
everything was fine.

Most recently and it is not fixing itself is that the electronic shut
off on the fuel injection pump is not working and I have to turn the
little black knob over the fuel filter to starve the engine out to
stop it.  Also but probably not related, the AC clutch is not turning
on.

Is there some kind of know mechanical or electrical problem with the
ignition switch or some kind of harness  problem (bad crimping of
connectors, etc.?) that could be causing this?