I have a 97 astro van (150k) that I have to replace the cap and rotor every
2 months. It runs fine with a new cap and rotor for about 1 month, Then it will start to miss out. It may miss for 15 mi., then shut it off for 1 hour and it will run fine... It act like there is moisture in the cap. It does not matter if it is raining or not.Could the seal in the distributor be bad? Would that let moisture get in?? The van sets outside at night.
I have never seen any sign of moisture or oil in the cap.
Kevin