Flashing check engine light

Possible causes - Faulty spark plug (s) - Faulty ignition coil (s) - Clogged or faulty fuel injector (s) - Intake air leak - Fuel injectors harness is open or shorted - Fuel Injectors circuit poor electrical connection - Ignition coils harness is open or shorted - Ignition coils circuit poor electrical connection - Insufficient cylinders compression - Incorrect fuel pressure

PLEASE READ IT ALL, ITS WORTH IT. To give a little background a few months ago, my car gave the code for misfire on cylinder 3 and bank 1 running rich. So i changed the coil pack and spark plug on that cylinder. For the first few weeks it ran good then started acting up a little for the first 2-5 miles in the morning then would run fine. A few days more and it started running rough, shaking, vibrating, a lotta hesitation, poor acceleration and loss of power dramatically. So i have the codes read again...... it shows random/multiple miss fire . And two codes for the maf and iat sensor (one was high output and the other low input). I change the maf sensor and those two codes clear for its diagnostics. The cars performance improved very slightly and was still reading multiple misfire. I change out the maf sensor again, the camshaft sensor, crankshaft sensor, pcv valve, cleaned the injectors, changed the other three spark plugs, and checked for vacuum leaks. A few times the car would pick up and run fine for a few minutes or several miles and mostly it happened on long stretches on road/highway before and after i changed all those parts. Still no change in the car. I was fixing to break down and carry it to a mechanic. I decided as a last ditch effort to just unplug the coil packs one by one and long behold the very same coil pack i just changed a few months ago made no difference in the idle when i unplugged it. So to be sure i switched the coil pack to another cylinder with the same result. Oh, i bought the expensive lifetime warranty pack just in case anyone is wondering. Morally of the story is.......just because the code reads misfire on cylinder 3 one week then random/multiple misfire the next, it could be the same exact issue throwing two completely different code numbers. I learned check the coil packs first its simple easy and caused me a lotta headache, research, and time. Hope this helps someone else.