I have 2011 Nitro 290 sport and Just recently lost top end speed. Use to get about 53 mph and now only get 40-42. Doesn’t get out of the whole as fast either. Engine doesn’t quit sound the same. Starts and runs ok. Took it to bass pro shop to try and get it repaired and they couldn’t figure it out. They did change out the diaphragm and spark plug wires, but engine still performing the same.