1996 F150 4X4 was starting to idle roughly before smoothing out. Local shop read the check engine light as O2 sensor failure. Replaced it with OEM sensor and went back to trailering a pallet of sod. Next day the truck idled and shuddered very roughly at start up and the check engine light on again. Any suggestions as to what to mention to the shop to check first? Truck has 166,000 miles, I am second owner.
I might recommend that you clean the Mass Airflow Sensor and clean your throttle with cleaner. It’s cheap and it it never hurts to clean up some dirty parts. If you need advise on how to do it, just watch Scotty’s video : How to make your car run better with spray cleaner
I’d also recommend you pull out a spark plug or two and just see what they look like. It’s about 45 minutes of your time. It could be something as simple as plugs not firing to the best of their ability.
Did you read the new code?
