Small Engines (Lawn Mowers, etc.): Engine Governor, briggs stratton, hp briggs

Question
I have a used mud motor with a 8-hp Briggs & Stratton IC engine for hunting in the marsh (recently purchased).  The engine starts easily, but would run unevenly when accelerated.  I had a mechanic at work put a carburetor kit in it, but it did not fix this problem.  After calling the fellow I bought it from, I learned that he had bent a wire (?) on the governor to get more rpm's and speed out of the engine.  I copied the instructions on adjusting the throttle/governor from the owners manual and gave it to the mechanic.  He adjusted accordingly, but now the engine runs unevenly at low speed, but seems to hold more steady at high speed. (I have not put the engine under stress to see if the governor compensates for the load)I would like to have the engine run smoothly at all speeds!  Any suggestions on what to look for or how to correctly adjust the governor.  The engine runs great if you hold the governor steady with your hand.  Thanks  

Answer
Do you know how old the engine is?  You can tell by the first two digets of the code number.
The first thing we do with an engine that is surging is clean the carb with carb cleaner and compressed air.  We completely dis-assemble the carb for cleaning.

Once the carb is clean we adjust the needles to get it running.  After the engine is warm we make some more slight adjustments and set the governor and idle speed with a tachometer.  This may be your problem.   Most Briggs engines idle at 1800-2000 RPM.   This is important to prevent surging.  Then we do the same thing for full throttle using an engine sales manual to set the governed RPM.

If someone has bent any governor parts then the governor spring may be defective.  How ever, this should not affect the idle circuit.

Do you know what the idle RPM is set to?
Let me know.
Eric