I just cleaned my carbs and re-installed, but I am still only getting 2000 RPM in forward. In neutral, I can momentarily rev the engine up to 4000, but under load I cannot get more than 2000 RPM. The engine is idling rough also. Should I try to clean the carbs again? I didn't use a rebuild kit, but when I put it back together, nothing leaked. The needle valve and float looked good, and the needle valve ran up and down smoothly when I lifted the float.