Q: Loss of power with flashing engine light

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When holding a speed of roughly 47-53 I get a consistent jerk like the engine is bogging down but I have no power loss and I receive no check engine light. If the jerking gets too violent then the engine immediately smooths itself out and a light comes on for one of my O2 sensors, probably just a lean misfire. What scares me is today it started acting where when holding 25-35 mph I get a huge loss of power and the tach bounces roughly +-800 rpm from where it was and the check engine light flashes until I am going slower than 25 or faster than 35. If I accelerate out of the speed zone I suddenly get all my power back in one jerk and once even got a loud metal on metal bang. The car sat in Florida for at least two months with the same tank of gas before I bought it and the previous owner did nothing but oil changes and air filters for maintenance so it's most likely the original spark plugs from 158k ago. The only things I can think of is plug misfire or gunked up injectors

My car has 158000 miles.
My car has an automatic transmission.

What you are describing sounds like a dirty or faulty mass air flow sensor. The mass air flow sensor monitors air intake as it is mixed with fuel prior to being injected into the motor. This sensor relays vital information to the ECM which uses this to make adjustments to fuel supply to the motor. A dirty or faulty sensor can cause an imbalanced air/fuel load to be supplied to the motor which results in an over fueling or under fueling situation depending on the conditions. This type of inconsistent fuel supply to the motor may cause a hesitation, loss of power, a jerking reaction, potentially a bit of black exhaust smoke and typically a strong smell of fuel when this sensor is malfunctioning. I would suggest having a professional from Your Mechanic come to your home to diagnose and inspect your vehicle.

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