We have an '94 850 Turbo with 103K miles. In the last 3 weeks it has developed a problem starting. It often happens after the car has sat for one hour. It doesn't happen after it has sat for days without running. My mechanic, is having a tough time finding the problem, because after I have it towed to his shop, it starts. And, of course, it started everytime he tried it during a week at his shop. Then I drove it home (about 2 miles), and an hour later it wouldn't start. He has tried replacing the the O2 sensor, since it registered some errors, but that hasn't corrected the problem. He gave me a spare relay to try, but that didn't correct it.

This is getting expensive and frustrating. Any ideas?