2003 Mazda Tribute P0316, P0430, P0174 - Rough Acceleration and Misfire Issues
I've been experiencing ongoing issues with my 2003 Mazda Tribute. After replacing the fuel filter, the problem seemed to improve temporarily, but the check engine light remains on. A visit to AutoZone revealed several diagnostic codes: P0174 (rich mixture in bank 2), P0316 (misfire during initial start-up), P0300 (random misfires), P0305 and P0306 (specific cylinder misfires), and P0430 (diesel particulate filter issue). The car starts smoothly and idles fine, but when driving, I experience rough acceleration. On cold starts, the vehicle drives well with gentle throttle input; however, once warmed up, it struggles to accelerate—often failing to exceed 15–20 mph. Acceleration becomes jerky, and the engine seems reluctant to shift or respond. The codes indicate a misfire occurring specifically in cylinders 5 and 6 (bank 2). Before replacing spark plugs, I'd like to know if others have encountered similar symptoms with straightforward fixes. Any insights into potential causes or solutions would be greatly appreciated.
Check for vacuum leaks and verify fuel pressure—restricted injectors in cylinders 5 and 6 are a possibility. Remove spark plugs and inspect them for wet, dry, or black/tan deposits. AutoZone sells parts but does not perform vehicle diagnostics; they often recommend replacements without first troubleshooting the root cause.