For some time, our 1989 240 wagon has had an intermittent electrical problem that results in the car stalling. Usually it will start and run the next day as if nothing ever happened.

When the problem begins, the windshield wipers, if on, start to slow down. The radio lights go off, the fuel gauge quits working, the engine starts to miss then dies shortly thereafter.

The main power relay was replaced in December 2006. The spark plugs and wires are new. The 25-amp fuse is in an IPD waterproof housing. I just replaced the brushes and internal voltage regulator in the alternator. The car runs great when it runs, and I'm assuming the alternator is charging since none of the idiot lights come on when it's running, but since I did the work on the alternator the idle is erratic.

Yesterday it died again. My wife was on her way to work on the Interstate, and it started to run rough. She looked at the gas gauge, which had dropped to zero. As she exited to go to a gas station, the needle went back up to 1/4 tank. She filled up and drove the rest of the way to work without incident.

On her way home from work, she got about a mile down the road and noticed the radio light go off; the windshield wipers slowed, the engine started missing then died right after she pulled into a church parking lot. She had it hooked to a Volvo-friendly mechanic we use, which is where it is now.

Any ideas?