Nissan Repair: 97 Nissan Pickup 2.4L, oil contamination, nissan pickup

Question
Got a 97 nissan pickup with a 2.4L that will not pass emissions due to misfire cyl4.  we have done a tune up on the vehicle 4 months ago and have checked compression and all the basics up to including swaping the injectors.  the code still appears, but has no miss what so ever.  was told by a Nissan tech that the distibutor is to blame and it is due to water gathering in it and not being able to drain.  do you know any other items to check.  i own a shop and have do have experience master techs on staff, who agree the distributor may be the issue.

Answer
Preston,

I would remove the distributor and disassemble the top.  Remove the rotor post first and then the cover under it.  Note how it goes together since it is simple but clocked.  Once the cover is off you can see the optical shutter wheel and pickup and receiver.  If you clean these components with tuner cleaner (Radio Shack) and then blow out the oil contamination and such and then reassemble, it should run fine until the crud works its way back up the shaft to cause the problem again.  Rebuilt distributors for Nissans are quite expensive so this will let you know if you have found the problem.  But, if that is what the code says it is then the solution is above.