I just bought a used 2000 G20 with 100,000 mi. Most of the time it sounds fine, but sometimes when I start the car it starts misfiring and driving rough. This continues until I drive the car a couple of miles then it stops and drives ok until I restart the car. It doesnt do it everytime, but it was doing it a lot when it got really hot out (mid 80s and up). Its also worse if I start the car with the air on. I only have a few more days to exchange the car but the weather has cooled off (70s) and its not doing it anymore. My regular mechanic cant figure it out. Does anyone know if this is potentially a serious (and expensive!) problem or is it more likely bad plugs or bad gas or something minor? I havent taken it to the Infiniti dealership mechanic yet because its not been acting up but Id hate it if it got really bad as soon as I could no longer exchange it. Advice anyone?!? Thanks!
