Nissan Repair: 93 300ZX NA-engine runs rough, low pull in lower rmp range, rpms increase, 300zx

Question
I have a 93 normally aspirate 300ZX. Just recently is has been running pretty
rough and the engine vibrates excessively as the RPMs increase. Besides
running rough, the pull in the lower RPMs is very low. My acceleration at best
is casual. Included in the symptoms are hesitation and bogging down. I will
go ahead and change out the spark plugs, but I have a feeling there is more
to it than just the spark plugs. I would rather do all the work that I can myself
before bringing it in to a shop. Any information would really be appreciated.

Answer
Ritche,

My bet would be the distributor has oil on the optics and that is causing the problem with vibration and rough running.  Take the cap, rotor, rotor post, and cover off and look for oil on the optical shutter wheel.  There is a seal in the bottom of the distributor that fails with age.  Replace the unit with a rebuilt distributor if there is oil.  If not, email me back with what you find.