Combines RPM fluctuations

I have had this happen before. Go back to the relays in the enginge compartment, and wiggle it with the engine at high idle. If the enginge cuts out run a ground wire from the screw holding it to the machine to the negitive post of the battery. If that does not cure it there is a possibility that the positive battery cable going to the starter is bad. But it could also be that the speed sensor in the injection pump is going bad, which means pulling the pump off and sending it to a repair center. this was on the early pumps though because the later ones use the engine speed sensor on the timing cover.

you have done the filters does this include the one in the tank also check the airvent is clear...on the 9500 in the engine compartment by the back wall to the control box you will find a large plug check to see if it is 1...clean inside no corrosion 2 . tight and water proof we ad two 9500 do the same thing both times it was the plug good luck