Hey Scotty, i have a 2010 ford flex 3.5 liters. My check engine light was flashing so went autozone and they said it was cylinder 1 not firing properly . I replaced coil pack and spark plug. Car ran good and light went off. Now its back flashing and running rough. Havent gone yet to descended. Any ideas?

could be bad fuel injector on that cylinder, intake manifold gasket leak, head gasket leak, computer circuit failure on ignition or fuel injection system. Good luck. Pray it's not the engine going out on cylinder 1

But that code says coil pack. Are the codes vague? How would i find out if its 1 of the things u mentioned