Im experiencing hesitation. my distributor was changed out about50,000 milesago

what to replace if oil is leaking into the ditributor

A distributor should last longer than 50K, but lack of proper oil changes will speed up wear on anything related. First verify IF there is oil that could be shorting out the distributor. It will alsmot always leak out-- easy to see. If so, then it will depend on the design, but usually requires a new or rebuilt distributor. If left as is, the poor running will cause other problems, including engine damage. Until that point: high emissions, poor MPG, loss of power and decreased safety are key examples. Sounds like you need to find a shop right away-- word to the wise-- it's money well spent.