[Flatrater]

Misfires over time will destroy the convertor. Your bad wire could of been the cause of your cat going bad. Convertors do not go bad on their own something causes the convertor to go bad. Replacing the cat without repairing the causes is like putting a bandaid on a cut. The cut is still there and bleeding, you just can't see it. I have changed many convertors over the years and 90% of the time I figured out what caused the cat to fail.

As for cleaning the MAF sensor that is a common pratice that I reccomend to any owner having problems with idle, fuel economy, and several other concerns along with a fuel filter change if not done for more than a year. This can be done by the car owner.

GM also stands behind this procedure. Along with MAF cleaning I clean the IAC and throttle bore.