PLYMOUTH INSTRUMENT CLUSTER GAUGES TACHOMETER

On A 1988 Plymouth Voyager Se (v6 3.0l Engine)what Causes The Tachometer (rpm Gauge) Needle To Go Around And Not Accurately Show The Engine...

I Am Getting Kick Back At Idling, 30, 50, 70 Mph. Took It To A Shop And They Said Its The First Cyclinder That Is Misfiring And Needs...