Tuners have discovered the spark plug caps on Firecat models need to be all the way down onto the spark plug. If there is ANY ceramic showing from the outside of the plug, the cap is not on all the way. This will cause misfiring and overall poor performance. You need to push firmly on the cap while twisting back and forth very slightly to get it on all the way. The rubber seal should contact the metal shell of the plug.
Next one, check the plugs for cracks in the ceramic. If there are cracks, it will run as previously stated – not very well. Put in some new plugs.