As part of a recent tune-up, I had the injectors cleaned. After this tune-up, the car ran great, while it was warm. Next morning, new problem... for a couple of miles running cold, the car hesitates with no power while accelerating and backfires. It's been back to the mechanic twice and they haven't been able to correct the problem. Any ideas about what this problem might be and what they might have done to cause it?

How did he clean the injectors? If he removed them did he put new seals on the injectors?

replace the injector seals. They cost 5 bucks and take 10 minutes to put in. It can make a world of difference in how your car runs.

Thanks for the seals suggestion. I'll ask the mechanic.

I talked to the mechanic and found out that the injectors were cleaned with a solution in the fuel line, they were not removed. I asked him about the seals. He sprayed some carb cleaner or the like along the injector rail to check for leaks and found none.

A new twist to the saga... He found that the timing was WAY off from the spec on the engine sticker. He said the sticker specifed 12 +/- 2 degrees and it's set at 0. He's now telling me he thinks it's the timing, but I don't buy it since the problem started immediately after they had it in for a tune up.

Is there anything peculiar about cold running in this model that I should look for? This is not a Volvo mechanic, but is a reputable shop.They're scratching their heads and asking to have the car overnight (again!).