Hey gang, hoping for some help diagnosing this one. Cropped up on my new to me 2000 with 204k. It ran fine for a few weeks after I bought it and it sounds like it hadn't seen a ton of use from the PO, so I probably put more miles on it than it had seen in a year. Here's the sequence of events:
- P0135 code for O2 heater circuit bank 1, sensor 1 (driver front if I understand correctly). Cleared the code so I didn't miss any other potential codes and it usually came back in ~20mi of driving.
- While waiting for new O2 sensors to show up, started noticing occasional power dips on the highway. Usually when on partial throttle, no noise, no vibration, nothing alarming, just feels like the power goes out from under me a little bit.
- Installed new front O2 sensors on both sides, figuring if one was going then might as well get the other while I'm down there.
- P0135 stayed cleared, but P0155 for O2 heater circuit bank 2, sensor 1 started coming on and power dips started getting a little more frequent. Power dip struck me as a potential fuel issue and I read a thread on here that mentioned that a fuel pump problem could also throw O2 codes so I ordered a new pump, strainer, and filter.
- Got new pump and filter installed yesterday (with the battery disconnected the whole time so I think ECU should have reset) and took it out for a spin and the truck was fine for the first 5-10 minutes then started idling really rough at stoplights. Popping it into N and holding revs above 1k kept it running OK.
- Tried driving to work today thinking that if the rough running was just at idle that freeway would be okay, I could maybe gather some more symptoms, and take a look at it over lunch but about 15mi into the trip it started clearly misfiring on the highway going up a slight incline.
