Have a B&S 20 HP engine that the compression release lever broke on. Cleaned everything out and put new camshaft in and everything back in exactly like suppose to be. New plug, new oil. Took carburetor apart and cleaned it all out and everything on it was good. Checked linkage and springs for carb, everything good and in the right place. Adjusted valves, they are good. Engine started fine but stays running at almost full throttle and cant be adjusted with the throttle control lever. Runs good just cant control engine speed. Cables and springs for all linkage is there and seems to works fine. Need some help. I cant figure this out.