So bought a 2014 ford mustang 6 speed 70k miles with a roush exhaust from out of state and drove it back 9 hours. On the way home as I was revving it to hear the popping from the exhaust then the engine light started flashing and went away so I pulled over to an autozone and no codes were detected. It was fine rest of the trip but about 30 mins from home I was doing a little pull out of a toll both and it started flashing again then stayed on. It seemed to happen when I go higher in RPMs and the exhaust pops. Long story short I got my coil and plugs changed. All was fine as I left the mechanic until about 30 mins into my little test drive and the light came back on and stayed again… codes P0301, P0300, P0305 all popped up. What do you guys think is going on?

 

What has been done to the car? Is everything stock? Is it the original engine?

 

Yes everything is stock. Just roush exhaust. Original engine as well.

 

cylinder 1 and 5 are misfiring. Now to do the detective work

 

What do you suggest I do?