Does the engine have a turbo?

If so, maybe that mechanic "turned in" the adjustment of the AFRC (air / fuel ratio control) (will have a boost hose going to it, on a turbo engine) This is mounted beside the electric shutoff solenoid, on a turbo style engine.

OR maybe he just "turned out" the fuel screw, under the medium size cover at the rear governor area. (This cover has two smaller bolts and one larger plug)Only need to remove the 2 little bolts and that cover will lift off. So, if you want less overall fuel, then remove this cover and loosen a small jam nut, and "turn in" (tighten clockwise) the adjustment screw that has the screwdriver slot on top of it.(don't forget to snug jam nut after adjustment) Start with either a 1/2 turn or 1 full turn, then go test drive it (keep track of how much, you turn, so if you have to return it to its original setting, then you know the total amount)

What is your air filter condition like?

If it's an engine with a timing advance unit, then maybe it has failed?

(3208 fuel screw_in paint program.jpg)

(3208 pump.jpg)

3208 fuel screw_in paint program.jpg (37KB - 1184 downloads)

3208 pump.jpg (34KB - 1701 downloads)