I have a 98 expedition with 177000, I drove it to the store and soon as i
made a u turn my check engine light start flashing, the it went solid. I drove it home and pulled the code, it gave my p0303. so i cleared the code & drove it to advance auto to see how much a coil pack will cost. the check engine light started flashing again, the it went solid. So i drove it home and pulled the code, this time its giving me p0171, p0303, p0304.
did anyone ever had this experience.

 

The P0171 is a lean reading from the o2 sensor. The 0303,0304 are cylinder 3 and 4 misfire. This could be leading to the o2 sensor reading. Coil packs look like they are in your future. You said you drove it home. How did it drive? Feel like it had power or lack of, was it kind of jerky when you gave it gas? Did you get some rain before the CEL came on? Make sure you don't have coolant dripping from the heater hoses onto the 3 & 4 cylinder packs. Really, you most likely have coil packs going bad. As long as you are replacing 1 you should replace all 8 so they are all new.

 

When i drove it home it was jerky, also lack of power too...