Ztmartin96

I’m working on a 2011 Bobcat 3400. At around 20mph it bogs down and loses all power. If you let off the gas and let it slow down, it’ll go again until 20mph. It use to not do this. Use to run 30mph+ no problem. I’ve replaced the fuel injector, fuel pump, spark plug, and air filter. Cleaned the throttle body, the fuel lines, and cleaned the fuel tank out. What am I missing? Any help would be greatly appreciated.