Rough idle, sluggish acceleration and misfiring are all signs of clogged fuel injectors. The fuel system has filters, but over time they become damaged by dirt and debris. Once this happens, the likelihood of the injectors becoming clogged increases.
The symptoms of a rough idle and sluggish acceleration can also be attributed to a clogged fuel filter, but actual misfiring, especially in a late model car, is more likely to mean that the injectors are clogged. The reason for this is that injectors do not clog in unison, meaning that one or two injectors are more clogged than the others. Under hard acceleration, this usually results in one or more cylinders misfiring. This is less apparent in older models as the simultaneous injection system allows unclogged injectors to make up for clogged ones. Performance is still affected, but it may not be as obvious initially.
Clogged fuel injectors can sometimes be caused by low quality gas without additives. To compensate for this, a fuel injector cleaner can be added to the fuel tank after every other fill-up; however, fuel injectors do eventually clog regardless of the gas used. At this point, it is best to have them cleaned by a professional repair shop.