Mark, at separate times I had a bad neutral safety switch and a bad starter solenoid. The symptoms with the bad neutral switch were that sometimes it would not turn the starter or make any noise whatsoever in Park. In neutral, it worked fine every time.
With the bad starter solenoid, it would intermittently not turn over or make any sounds no matter what I did. Then a few hours later, it would work fine. Go figure! To find out if it is the starter solenoid, connect a thin wire momentarily from the + battery terminal to the small terminal on the starter solenoid that is mounted on top of the starter. This will eliminate the neutral switch, ignition switch and wiring connections as possible sources. If nothing happens when you try this, it is most likely the solenoid at fault. Mine wasn't too tough to replace, I don't know about the turbo though. Before you start replacing anything, make sure that all connections from the battery to the rest of the car are absoulutely clean and in good condition.