OK , my car missed a couple times two weeks ago and slowly started getting worse and occuring moew often. My vavles are fine , lifters are fine. we changed spark plugs and wires because wires were old and the 3 month old spark plugs were shot because a lil too much gas, but the car ran fine before. this past winter i put a new cap and rotor on my motor so what the heck is wrong? the timing is fine. the motor is missing and backfiring at random. PLease help