Nissan Repair: Rough running no power, nissan frontier, test light

Question
I have a 2000 Nissan Frontier V6 108000 miles. The truck runs very rough at any speed. Gets worse the more you drive to the point it quits. The check engine light is not on. Changed plugs, wires and dist. cap, no change. Put a spark plug test light inline and noticed very irattic flashing. Tried other plug with the same results. Can you please help?

Answer
Lee,

If you do not have a good spark at the plugs the problem could be the distributor itself.  I would take the cap, rotor, rotor post and cover off and inspect for the presence of oil on the optics.  If there is oil it is contaminating the LED signal and thus a weak spark is the result.