It got cold here, 20 degrees (cold for us) and after sitting a day, my '99 V70 NA wouldn't start. I thought the battery was weak, so I charged it overnight and tried to start the car again in the morning. Still wouldn't fire. It warmed up during the day so I tried later. After a couple of tries, it sputtered, but would fire. I held the gas pedal down and cranked it again and it fired, but wouldn't idle. I had it keep the revs up up keep it running. I revved it again even though it was still cold. I got gray exhaust. After a minute or two, it settled down and idled well.

I've had similar starting trouble before when I would give the key a quick turn without waiting for the engine to fire. When I tried to start it after that, it didn't want to fire. When it did fire, it didn't want to idle. I thought this was some kind of computer problem.

Other than these occasional hard starts, the car starts and runs well. Any ideas? The car has about 115k miles on it and I've owned it for the last 30k. I had the timing belt changed, but have done little else. The dealer did the ignition recall and the headlight switch recall. About 10k ago, I ran some Techron through it, but that's it. What do you think? TIA.