This is probably the Service Bulletin the dealer was referring to...
Distributor - Surging, Bucking, or Intermittent Missing
18-16-92 Rev. A
Oct. 19, 1992
Surging, Bucking, Or Intermittent Missing
THIS BULLETIN SUPERSEDES TECHNICAL SERVICE BULLETIN 18-16-92 WHICH SHOULD BE REMOVED FROM YOUR FILES. REVISIONS ARE HIGHLIGHTED WITH **ASTERISKS**.
**THIS BULLETIN APPLIES TO 1992 VEHICLES EQUIPPED WITH 3.9L OR 5.2L MPI ENGINES AND 1993 VEHICLES EQUIPPED WITH 3.9L, 5.2L OR 5.9L MPI ENGINES.**
(AB) Ram Van/Wagon
(AD) Ram Pickup/Ramcharger
(ZJ) Grand Cherokee
Vehicles may exhibit surging, light bucking, or intermittent engine misfiring. This will most likely occur when the vehicle is at operating temperature, and under a light load at approximately 2000 RPM. This condition may be caused by a mis-indexed distributor. The following procedure is an alternative to the indexing procedure outlined in the service manual.
This bulletin outlines an alternative distributor indexing procedure.
1. Connect a voltmeter to the distributor sensor connector by removing the end seal and carefully back probing the connector. Connect the positive lead to the sensor output pin (pin 3, either a tan wire with a yellow tracer or a gray wire, depending on vehicle application). Connect the negative lead to the sensor ground pin (pin 2, a black wire with a light blue tracer).
2. Rotate the engine clockwise as viewed from the front, until the number one piston is at Top Dead Center (TDC) of the compression stroke. The timing mark on the vibration damper should line up with the zero degree (TDC) mark on the timing chain case cover.
3. Continue to rotate the engine slowly clockwise until the V6 or V8 mark (depending on engine type) lines up with the zero degree (TDC) mark on the timing chain case cover. The V8 mark is 17.5°after TDC and the V6 mark is 147°after TDC.
DO NOT ROTATE THE ENGINE COUNTER CLOCKWISE. IF THE ENGINE IS ROTATED BEYOND THE MARK, RETURN TO STEP 2 AND REPEAT THE PROCEDURE.
4. Loosen the distributor clamp bolt.
5. With the ignition switch in the ON position, rotate the distributor slightly in either direction until the voltmeter switches between the sensor transition point of 0 and 5 volts.
6. Adjust the distributor as close as possible to either side of this transition point and tighten the distributor clamp bolt to 170-230 in.lbs. (19-26 N-m).
Reimbursable within the provisions of the warranty.
Labor Operation No. 08-15-02-90
AD, AN ........ 0.3 Hrs.
AB ........... 0.4 Hrs.
51 - Improperly Installed