While soliciting theories about the "Brake Failure" light that will intermittently plague my car, I discovered that I probably have a bad or dying brake servo--when I pump the brake pedal while in park, I can get the car's idle to drop precipitously.

Last night, after the car had been sitting for between 48 and 72 hours, I prepared to drive to get something to eat. When I turned on the car, the "Brake Failure" light was illuminated much brighter than it had been before. Previously, the "Parking Brake" light had been about twice as bright as the "Brake Failure" warning, but this time they were a bit closer to being equally illuminated.

I turned the car back off, since I was on the phone and I didn't want to go anywhere until I could give my full attention to driving, should I have problems. I finished up about five minutes later, and when I turned on the car this time, no idiot lights lit up!

I turned on the headlights but didn't head out quite yet. I knew that the brake servo was still probably not better, so I pumped the pedal a few times and got the car to stall, which hadn't happened before. Also, it seemed to lurch forward a few inches from its parking spot, but it *could* have been my imagination combined with the engine sputtering and dying.

I turned the car back on, which didn't start up quite as easily since I left the headlights on, but it cranked and I prepared to head out. The "Brake Failure" light remained off for the short trip to eat.

When I got back in the car about twenty minutes later, the "Brake Failure" light again came on and remained illuminated for the trip back home. However, at no point did I notice any lessened braking ability.

Does anyone have any idea what's wrong with my car? Could a bad brake servo cause the "Brake Failure" light to activate? Why did the idiot light go away after starting the car, then turning it off for a short while? Why did it come back on later?

I'm going to take the car to a mechanic soon, since it's almost certain I've got that bad brake servo, and I'm not going to be able to replace it myself. But, if that's not causing the problem, then replacing the part probably won't eliminate the warning light. What do I need to do?
--
'89 244 GL -- 105,XXX miles (see profile for info on car)