I have a 2000 dakota quad cab 2 wd, 4.7 auto. I purchased the truck with 60,000 miles on it. I have driven it for about a year with no issures. Then the truck started running rough. Dealer showed injection system throwing false codes. Replaced throttle body sensor, reprogramed PCM. Then started showing upstream left bank o2 faults. Changed 02 sensor, cleared faults. Two days later o2 faults back. When this happpens, left bank injector system goes extremely rich. Dealer changed same o2 sensor, cleared up again. Week later same thing. Dealer checked wiring harness, all injectors, PCM, replaced same o2 sensor, cleared up, 2 days later same thing. Dealer says next step to replace Catalytic system. Anyone been down this road?

 

you can have a backpressure test done to see if the cats are getting plugged up. most muffler shops should be able to do this. i had mine checked and i have 94000 miles and it read 0 psi for back pressure. but my mileage is going down hill fast, so i may need to replace the o2 sensors. i i guess they get worn out pretty quick up here in the frozen north. good luck!