My regular mechanic is out of town for a time and my '85 190E developed some weird problems (simultaneously). The ignition key became difficult to engage and turn to start. Now as I drive over any period of time, the car completely stalls. After a few minutes, it would start again (I still had to jiggle the key to get the ignition lock to turn), and I could get home. Last night it stalled and now won't start. A roadside assistance tech told me it was some anti-theft function in the switch and I would need a new switch. Is this a common thing?