Hi guys. I have a Craftsman Briggs & Stratton 14-20 hp mulching rider mower. I have had little to no problems until recently. The problem now is that the engine quickly starts and turns over....but as soon as put into gear and let up on the brake to go, the engine stalls out. What's more is that if I engage the mower blades the engine stalls out as well. Belt issue maybe? Any suggestions are appreciated.