Small Engines (Lawn Mowers, etc.): LX178 Low Power, line filter, plug wires

Question
Have LX178, Kawa 15hp, liq cool, twin cyl. Starts perfectly, runs poorly. Hardly
has power to move the machine. Chassis 178X042474; engine FD440V-AS00,
FD440V007099. Suspecting fouled gas line, I cleaned tank, line, in-line filter,
filled with fresh gas. No improvement. Doesn't burn oil. I suspect a carb
problem. What think you? Appreciate your thoughts.

Answer
More likely a dead cylinder than a carb problem.  Start the tractor and pull the plug wires one at a time.  If you pull the wire and nothing changes that is the bad side.  If you pull the wire and the engine dies that is the good side.  Check for spark on the bad side. I'm guessing you won't have any.  Replace the coil on the no spark side.