I picked up a very nice 1994 C220 for my mom for her 80th birthday. The car had been sitting for about a year due to some electrical problems. I got the car back to my shop, charged the battery, and got it fired up. Checked the alternator output and it was about 7 volts so I replaced the alternator and the battery which would not hold a charge. I figured problem solved until I tried starting the car several days later and it cranked over fine but would not start. I checked for fuel and the pump was working fine and then checked to find it had no spark. I left the car for a couple of weeks and tried to start it again and this time the starter would not engage as if the battery was dead. Checked the battery and it was at full 12 volts. I thought maybe it was the ignition switch. I replaced the switch and the car started fine again and I figured problem solved. I tried to start the car today after it sat inside the garage for a couple of weeks and again the car turns over but will not start. I'm guessing no spark again. It's definitely an intermittent problem. My good mechanic friend suspects the crankshaft sensor. Any ideas??