2002 Ford F150, 4.2L/auto 2WD. Approx. 213K miles.
Background: did intake gaskets on this truck about 2 years ago and has run well since. The downstream O2 sensors were hacked off during an engine swap before it came under my care but that hasn't affected its operation since, that I could tell.
Recently it began to "cough" or have a slight stumble when under load, at speed, and a lean code showed up on both banks. No visible vacuum leaks, no response to carb. cleaner sprayed around the intake, etc. Upon finding fuel pressure at the minimum allowable value with quick leak-down but 80 PSI and no leakdown with the return plugged, I replaced the fuel pressure regulator - no improvement to the lean/stumble.
Upon watching the sensor data, the upstream O2's aren't acting at all like they should, and I'm seeing momentary, random voltage gaps in TPS and MAF without touching anything. After observing this I'm hesitant to start spending money looking for air leaks or buying sensors if it could be a larger electronic problem. Any advice?
Background: did intake gaskets on this truck about 2 years ago and has run well since. The downstream O2 sensors were hacked off during an engine swap before it came under my care but that hasn't affected its operation since, that I could tell.
Recently it began to "cough" or have a slight stumble when under load, at speed, and a lean code showed up on both banks. No visible vacuum leaks, no response to carb. cleaner sprayed around the intake, etc. Upon finding fuel pressure at the minimum allowable value with quick leak-down but 80 PSI and no leakdown with the return plugged, I replaced the fuel pressure regulator - no improvement to the lean/stumble.
Upon watching the sensor data, the upstream O2's aren't acting at all like they should, and I'm seeing momentary, random voltage gaps in TPS and MAF without touching anything. After observing this I'm hesitant to start spending money looking for air leaks or buying sensors if it could be a larger electronic problem. Any advice?