OK, some background:

1. 2011 PF Silver Edition. Bought used a few months ago with 123K
2. (Potentially) Electrical systems things I have dealt with thus far (as background)
I had to buy a new key fob and have it programmed to my car.

I had to replace the MAF sensor a couple of months ago.
I had a no start condition in cold weather. Cranked but wouldn't catch then battery would become too weak to crank anymore and car
wouldn't start. Though battery was reading as still "good, I replaced it with a new battery. This has "solved" that problem so far.

Current problem. Car has been running fine. The only thing I have noticed occasionally is a stumble in the idle on occasion. Otherwise the car has been running great. Today I had a weird situation where I was driving normally, car was warmed up (not that cold today anyway). I stopped for a stoplight and out of nowhere it stalled. I tried to restart and all it would do is crank but not start. I tried for about fifteen minutes and gave up. A good samaritan helped me push the car to the side of the road. I arranged for AAA to come get the car and bring it to my mechanic. About two hours later the tow truck driver called to say he was picking up the PF and that it had started right up for him. I don't have any CEL on right now. What the hell can this be? Having a car with random electrical gremlins is not something I want to deal with. The forums seem to suggest it could be the crank or camshaft sensors. I don' t have a code for those as far as I know. Other than those things, what else would cause these strange symptoms? Dying sensors? Dying fuel pump? It's really frustrating.

Yes, it was the crankshaft position sensor.

thanks for the follow up. And it's not just the R51. I can recall this same issue with any vehicle that has a failing one.

I'm a bit surprised that there wasn't a CEL.

It's the same with the camshaft position sensors. When one side goes, the other seems to follow shortly afterwards. Not sure how it happens, but others have had it, and it happened to me as well.

Cheers!

Yeah, the mechanic said they often don't throw a CEL though he did find a code for the CPS stored. He said it probably had to happen more often to throw a cell. He said the same thing, that with the CPS when it goes bad it's often a no code situation. The car probably always had a failing CPS since I bought it because the way it revs and idles now is much smoother than before. I had never owned a PF so didn't know it wasn't normal.

Geometry Dash These sensors can fail intermittently before completely failing, which can cause random stalling and no-start conditions.