'04 R3, about 115k miles. Ran fine yesterday, but starting this AM, it will either not start, start and die immediately, or start and run for a bit (up to maybe a minute) and die. When it DOES run, it might run smooth or run very rough, but never runs for more than a minute or two before stalling.

Hooked up INPA to check codes, and the only thing present is:
1397 Cruise Control Input Circuit
Error frequency 1
Distance since last blah blah blah 0.00km
Engine speed 2310.oo
Vehicle speed 0.0 km/h
intake mani absolute pressure 364.39 hPa
Short to V batt
sporadic error
I'm very much a newbie with INPA, but based on the "distance since..." and vehicle speed numbers it sure looks like this happened today, coinciding with the start of the trouble. But I can't imagine what the cruise control would have to do with this when it's not turned on. If this were a carbureted car I would suspect a clogged fuel filter or failing pump, but wouldn't that throw some sort of a code from the fuel system?

Any ideas or tips to diagnose will be very much appreciated. As noted, I do have INPA but don't know it very well, but there's a lot of data there that I could monitor (f'rinstance, I watched the "engine roughness" screen for a minute while the engine was stumbling and sputtering, and the roughness was occurring intermittently on all four cylinders, on which basis I don't think it's a bad spark plug or injector.)

 

Update - cleared the codes, tried a few restarts (actually started once, ran rough as hell, died), checked codes, and found:

821 Crankshaft Position Sensor A circuit....
...
no signal detected
fault present
warning lamp state

Then I cleared that code, tried a few more starts, and the code came right back. This is starting to make a LOT more sense now. Presumably I've just watched my CPS die and need to order a new one. Does anybody think there are any other tests I should do beforehand, or that I'm not on the right track?

 

Did replacing the Crankshaft Position Sensor solve this issue?