I woke up early this morning to run some tests on the car.

Idling voltage with assumed bad ignition coil is 14.1V.

I checked all spark plug wire resistances and they were all within 1000Kohm - 1100Kohm range.

I also checked resistance across ignition coil. The 10mm and 8mm had 0.5ohms of resistance and 8mm to ignition lead wire had around 9Kohms of resistance.

I also checked the resistance of the 4 pole EZL plug. They were all within 1V of battery voltage (12.2V). Terminals 15 and 31 had 11.9V and terminals 16 and 31 had 11.88V.

I ended up swapping the ignition coil from my running 300E and started up the 190E just fine. It idled for about 10 mins and engine got warm. I shut it off and went to start the 300E which fired up without a problem with the presumably bad ignition coil (even drove it to work 30 mins away). When I went back to try to start the 190E, it would not turn over anymore.

So problem is not ignition coil anymore, perhaps the crankshaft position sensor? Strange because I replaced the CPS about 3 years ago when I was having cranking problems: http://www.peachparts.com/shopforum/showthread.php?t=239318

I will test the resistance of the wire when I return home.