Ok, drivin to work this morning and boom... the check engine light comes on again... it reads 67 Catalyst System.

it did this about a month ago also, i changed the front 02 sensor (thats what Autozone told me to do) and reset the ecu... it's been off until today!

now what could be the problem? it's a new cat and muff and front 02... all there is left is the rear O2 RIGHT?

Thanks everyone!