I have a winch with an 8HP Briggs & Stratton and a TAV2 torque converter. Bought it brand new in 2009. The problem I'm now having with it is that it's not able hold/maintain the higher RPMs to pull a rider continuously through the ride. I've changed the oil, fuel, & spark plug. But the problem persists! has anybody had this issue and/or have an idea to help me out?