Small Engines (Lawn Mowers, etc.): toro proline lawn mower engine surging, lawn mower engine, fuel filter

Question
I have a commercial lawn mower that keeps surging and has no power.  It stops when going up or down hills.  I changed the spark, I cleaned the air filter.  I adjusted the throttle.  It barely has power.  Where do I go from here?

Answer
Well I would need to know the hp of the engine? As well as have it in front of me to really tell for sure.But if I had to guess I would say it has a clogged carburetor? Or fuel filter? But as I said it depends on a lot of different aspects.You can try a new filter and or clean the carburetor but it may require a professional in your area to determine the problem.I hope this helps and good luck,Jason