I have a '95 850 GLT sedan with 118K miles. This is a long story and I appreciate those who read it.

History: Check Engine Light first came on with the "Rear Oxygen Sensor" code in May or June 2006. The car passed emissions and the impression I was given by the state inspection mechanic was that there was no impact on driveability or performance. I wondered if a loose wire/ poor connection was at fault.

July 2006: Delivery van backs into my car, necessitating the replacement of both doors on the passenger side. The battery problems started around this time. I don't drive the car very much, often only cranking it up twice a week to observe NYC's alternate-side-of-street parking rules. If the car sits for three to five days, the battery is too weak to start the car. I observed that the rear passenger door did not always latch completely and perhaps the side panel light remained 'on' when the door was shut. Or, the reading lights would stay on if in the "door open" position even though the door was closed. About five months ago, there was a dead battery incident; it was easier to put in a new battery than get a jump, so that's what I did.

For many months I enjoyed no battery problems because I was careful to start the car every two days and I made ABSOLUTELY 100% CERTAIN that the rear passenger door knew it was closed (the 'courtesy' light was off) whenever I turned off the ignition. Around the Thanksgiving holiday, I let the car sit too long so once again: a dead battery and a call to AAA for a jump. Then, a few days later, on a cold morning it started right up, but for the first time ever in my experience with the car it sputtered and ran very rough and stalled in idle. It re-started immediately. It re-stalled immediately. It re-started and I figured out to rev it in park enough to make it across the street before stalling again.

Friday, Dec. 15, 2007: Took car to Paul's Volvo in Hawthorne, NJ . Asked for "electrical system diagnositic" for problems with interior lights, the rear oxygen sensor and the mysterious battery drain or not-charging problem. I checked the codes myself last week and the only code was the rear sensor.

When I got there a Paul's service rep. told me they don't clean engines. Maybe I didn't use the right terminology. I asked for an "electrical system diagnostic" and explained the symptoms. After a mechanic spent some time with my car, a Paul's rep. came and told me that not only had the rear sensor failed but also the front sensor had failed, and that replacing one without the other was useless; it would be $700 to replace both. Paul's also suggested a $475 tune-up, a $200 winter-izing and a right engine mount replacement for a total of $1700!. I OK'd the sensors and the engine mount replacement but skipped the tune-up and winter-izing, as they were explained to me as "nice to have" but not critical.

After I paid the $1100 bill: First thing I noticed (besides no CEL) was a new fuel-like odor inside the car. About 15 minutes down the highway, driving about 60 mph, I had to brake suddenly and I had quite a scare -- it seemed that I pushed the brake pedal way down, much further than usual and that it took much longer (distance) for me to slow down -- I barely missed the car that changed into my lane. What if any connection to the repairwork (or original symptoms) do braking distance or brake pedal resistance have?

Sunday afternoon (48 hours elapsed since previous drive): Car starts immediately, then stalls the first time I idle at a stop light. Restarts, re-stalls, restarts, restalls. Everytime I had to idle and didn't beat the stall into Park. In Park, I could rev the engine and keep the car alive. I limped back to my block and re-parked the car.

Monday morning (~16 hours elapsed): I called Paul's service dept. and reported the stalls and weird braking experience. Service rep. told me to bring the car back for a second look. At 9:30 am, I had to move the car for alt-side-parking. It started right up, and drove (albeit a short distance) with no problems. Idle in park was no problem.

I 've looked at Forums and FAQs on Brickboard but I don't feel prepared for my return visit to Paul's service dept. What do you think is going on? What should I ask the Paul's mechanic to do? I wonder if the tune-up was more critical after all. I'm going to ask if the mechanic measured the current as described in so many of the forum posts and really did a nitty-gritty electrical diagnostic or just put some clips on the battery (that's what appeared on the bill). Did the front oxygen sensor really need replacing when there was no CEL code for it?