Need help, miss firing and given code P0355
So the other day i pick up my old jeep from my mom and drive it to work fine. got off work, started it and started miss firing kinda bad. i got a little code reader from my friend that hooks up to my phone and it gave me code P0355 ignition coil f primary/secondary circuit. i figured it was a bad coil so got a new one and swapped it into cylinder 5 from what auto zone said the code came up with and did nothing. i pulled the plug and it was covered in carbon. me and my dad replaced all the plugs bout 2 months ago, also tried to change the fuel filter but couldnt get the old one off.
Can anyone help me? i need to get it fixed by Wednesday morning.
Oh and it is a 2001 Grand Cherokee Limited 4.7l all wheel all time with like 190k miles