My check engine light came on last night and the car started missing a
little at low rpm. Advance put it on the computer and it said cylinder
#4 was misfiring. Replaced plugs, no difference. He said the other
possibilities would be either wires or a bad #4 fuel injector. Does this
sound right? Is replacing a fuel injector a difficult and/or expensive
thing? Thanks for any impute.

                  Jim