Nissan Repair: nissan altima repair, nissan altima, distributor shaft

Question
i have a 2001 altima. it jerks real bad when put in gear.
also in park but not near as bad.. i have changed gas filter, spark plugs, plug wires, distributor, rotary cap, and distributor button... have also ran HEET in gas tank to remove water if any.. it still jerks.. code reads multiple engine fire.. is it carburetor, injectors, or brain...? or should i go put it on a computer? or what would you say it is?

Answer
Buck,

Probably the distributor is defective.  Nissan uses an optical shutter wheel with an LED pickup and receiver.  The distributor shaft seal fails and then the oil gets on the optics causing multiple cylinder misfire.  If you have a V6 and it is doing it replace the coils as Nissan had a problem with coils in the 1999 to 2001 range cars.  Email me back if you need more.