Posting for a friend...

He has a 1994 Impreza which doesn't like to start after being driven and then turned off for short periods of time. Cold morning starts are fine. If he lets it sit for an hour or so, it will start on the next attempt.

So far, he has changed the fuel pump, O2 sensor, plugs, fuel filter, air filter, cleaned the air flow sensor and switched to premium fuel and still the problem persists. We did a check over the motor and all of the vacuum hoses look fine and fittings are tight as well. I would like to think that the problem may be electrical, but the fuel pump primes with every turn of the key and every cylinder is getting spark. When the car starts, it runs fine.

Any ideas?

 

The fix was changing the crank sensor ($30).