Nissan Repair: Stuttering Stanza, 1992 nissan stanza, nissan stanza

Question
I have a 1992 Nissan Stanza with an automatic transmission.  When I try to cruise at constant speed in high gear it "stutters" --  irregular but frequent jerking forward / backward.  The problem doesn't occur if speeding up or slowing down, or in other gears.  What could be causing this?

Answer
Kevin,

If the plugs are recently changed then I would say the distributor is contaminated with oil.  I had a Stanza, great car, and eventually, the distributor shaft seal fails and oil gets into the optical shutter wheel and messes up the firing of the plugs.  Nissan used an otical pickup and a shutter wheel to signal the computer to fire the plugs.