My distributor is breaking up in the upper rpm at times. Can this be a coil or ignitor problem ? Or should I just get a new aftermarket distributor ? I was thinking about another used oem but they are all 10+ years old units.

 

USUALLY higher rpm stumbles are the result of a bad coil. But I guarantee nothing with out testing.



With that said,Id buy new aftermarket.

 

Need to know what you drive. 4.6 and 5.4 Ford Tritons are known for this problem.

A stumble is the result of one and perhaps two cylinders misfiring. This will usually produce stall-like conditions. In the situation you bring up, it sounds like you have a single cylinder break up, which could mean anything after the coil itself (since the others would work).

The causes tend to be numerous without more information.

 

Year, make, model, ecu, mod, last tune up, Check engine lights?

 

Aftermarket distributors are usually junk. They maybe ok for a stock engine but tuning with one is horrible. The cam/crank sensors are noisy, the coils are weak and fail at the slightest temp. They suck.