Misfiring posted by inf on June 10, 2008 at 03:16 AM
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instead of guessing, either buy an wideband o2 sensor, or take it to the shop and have the AFR determined. A shop could also put it on a scope and tell you which cylinders are missing. Make sure you have no vacuum leaks by doing a boost leak test. I'd also look at the temperature range and gap on the plugs, might be as simple as going to a hotter plug. If your AFR is ok and your plugs are fouled, they are probably not the right temperature range. Could tweak the timing a bit too. Then I'd focus on your AFR and plug temperature and gap. Get the temperature range and gap right will make a big difference, small changes can make a noticeable difference in idle. Realize too that tuning an engine for power often causes a rougher idle - what you gain in one range often takes from another.
