have a 2002 dodge ram 1500 4x4 I keep getting p308 codes. number 8 cylinder misfire. I have changed the plugs ,the plug wires and rotor and rotor cap. it will last about a month and I start getting the same code. anyone have any answers ?

 

What type of plugs are you using? What Gap are you setting them to?

If they are Platinum, that is likely your problem right there.

If you are using the proper spark plug and correct GAP, then it might be time to get a compression test done and see what is up with that Cylinder.