RE: Check engine light keeps coming on
Actually ~750rpm idle is normal for all model DSM's. A little low can be attributed to the weather sometimes. Is acceleration feel weird? Any strange noises? Also, a quick way to tell if a cylinder isn't firing, check to see if any black smoke is coming from the tail pipe. It'll come as like pulses of smoke, and may be kind of faint, but any black smoke will be the unburned fuel from the misfire. But hey, if garymitsu's suggestions don't find the problem, just come back and we'll try again!