1997 Jetta GT 2.0 Stopped running,cranks,will not start

Hi these models are notorious for crank sensors Situated front of engine near engine oil filter. Before they fail completely the engine will shut down as soon as your engine reaches operating temperature note. The crank sensor does not throw a code half the time. Even without check engine crank sensor is possible. To confirm it's not a fuel issue open flexible air intake pipe which leads to m.a.f. Sensor. ( mass air flow ). On the engine side spray a few seconds of air intake cleaner and crank the engine over if it runs a few seconds. Fuel issue.
Air intake cleaner spray can available auto parts store. Hope it helps some for diagnostic purposes.

Check for blockage on air intake system before and after air filter, had this problem a few times. Check coolant temperature sender reading with a diagnostic fault reader.won't register a fault as long as it's getting a reading but reading but reading may be incorrect. should be more or less ambient temp when cold. check injectors are spraying.

Checking for spark is really simple while fuel delivery is more complicated because of the the way it is metered for delivery. On VW's a fuel pump relay is used and a jumper cable connected to relay box. This controls the fuel pump to deliver fuel manually. With a fuel pressure gauge connected to the line from the pump continued withing the system, you assess whether you have correct fuel pressure, maintain it within a specif duration. Electronic fuel injectors do stick or stay open causing very poor or no start condition. Make sure you have fuel delivery since you are positive that spark is present.