My check engine light came on; the dealer checked the codes and found
three cyclinders misfiring.  After tune-up (all plugs were changed)
and the same day I drove 80 miles when the check engine light came on
again; the next day the dealer checked the code and found four
cyclinders misfiring!  The dealer needed the vehicle for a day but no
loaners were avaiable for me so I’m driving around (with engine light
on) for a week when the original fan-belt failed.  After having the
belt replaced, the check engine light has not come on (going on 4-days
and counting).

During this situation not once did I have any indication of misfires.
 I had a friend who had a code reader to check the cause the second
time and the results confirmed the dealer’s findings.  Can anyone
relate to misfirings regarding unusal code readings versus maintence
or (hard to believe) was it the fan belt?!