Made a quick stop, hopped in about a minute later to restart.
Key was hard to turn, so I turned it back, pulled it out, and reinserted. It's the only key I was given when I bought the car. Flipped key to start, shifted into reverse, and it died.

Now it cranks, fires, and might even idle slowly and roughly for 2-5 seconds. Immediately restarting usually results in the car cranking until the starter times out. I don't think it's the battery because I've now cranked it 20-30 times and it still cranks fine.

OBDII shows no codes on my Scangauge.
Don't have Carsoft or other MBZ specific code reader.

Any ideas? I suppose I could unplug MAF and see if that's the problem.
Jump the k40 so I know the fuel pump is running? If so, which terminals? (the car acts just like a w201 or w124 with bad fuel pump relay)
If it's a smartkey problem, do I have to tow to dealer and buy a new key?

What about CPS, can I test those by unplugging and going into limp mode?
Can it run without cam sensor if I unplug it?
Can it run without crank sensor if I unplug it? (obviously can't run with both unplugged at the same time)

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'79 300SD W116
'86 190E 2.3-16V W201
'92 300D 2.5 W124
'99 E320 4MATIC S210