If you have a multi-probe oscillscope and read wave forms, testing the Crank/Cam sensors simultaneously is a great way to see visually if they are working properly on their own and in relationship to each other as they should.
Here is a link to a fairly competent article concerning Crankshaft position sensors.
Crankshaft position sensor: how it works, symptoms, problems, testing (at https://www.samarins.com/glossary/crank_sensor.html )
The 2-wire (magnetic) CKP can be tested using a multimeter switched to Alternating current. Back probe the signal wire and ground. Remove a fuel pump fuse or relay so the car will not start, and then crank the engine while taking your voltage measurement. If you get a good reading when the CKP is working, you can use that as a reference point to spot a variation in voltage if you are lucky enough to get a reading when it does decide to fail. (This is a simple logical deduction I use in some cases if exact service specs are unavailable.)
You can also resistance check the CKP, but it's not a guaranteed test for an intermittently failing CKP.
Also take note as mentioned in the article that what can appear to be a defective CKP, could in fact be a faulty flex plate, reluctor ring, or even the crankshaft itself.
It's variables such as these that can make for a wild goose chase if you're not thorough and informed.
Another example being that a catalyst whose honeycomb substrate has super heated and fused together can form a heavy duty blockage/barrier, causing exhaust flow restriction and backpressure into the cylinders, which depending on the severity of the blockage can cause issues such as overheating, stalling, misfiring, damage to gaskets, etc. You can have someone step on the gas to about 2,000 RPM, and feel for a hot, restricted flow, or any sulphuric smells.
I do not know if this applies to your vehicle or not, but in certain vehicles a faulty 02 sensor will shut down the engine, in which case the engine will generally need to cool before it will start again. However you should find a code stored for your o2 if this is the case.
When dealing with any stalling engine or crank but no start, it's usually a great idea to always cover your basics. Air intake and vaccuum, Fuel, filter, pump, pressure check, injectors, etc. Compression, spark/plugs/wires/coil(s)distribution...all are worth looking into.
I had a 95 Geo Metro with a bad magnetic type CKP, and no matter what I did, it would not die or fail to start for me whenever I was testing the CKP! However it would randomly die, and fail to start here and there, or run for hours without an issue. Long story short, the water pump was leaking onto the CKP. The CKP and water pump were replaced, fortunately solving the problem.
I hope you get it figured out.