Have a 10 HP (model 220707 type 0641-01). Was leaking gas from the carb. Installed a carb kit and that cleaned that up. Now I get an engine surge at all speed ranges, seems like the engine starves for gas for a second. under load with me on the unit and the mower engaged the engines runs good, strong and steady. The unit sat for a couple of years before I purchased. Cleaned out the tank and put new fuel filter in before gas or trying to start. Suggestions?