I recently bought an 09 lariat with 5.4L and 4x4. Ive got a check engine light for the o2 sensor on passenger side before the cat. Hooked up scanner and all o2's are reading just fine, nothing out of the norm and scanner not showing any misfires. However when I heavily accelerate(pedal almost to the floor) the truck attempts to go but then starts shaking and the check engine light flashes. When this happens I cannot accelerate and have to coast and let the check engine light stop flashing. Truck drives fine other than when trying to heavily accelerate. Anyone have the same problem or know what the problem is?

 

Check engine light flashing is a misfire, check for codes again. Don’t diagnose o2 codes until misfire is fixed. Also o2 heater circuit will cause a CEL, but you won’t be able to see a issue monitoring pids......