You don't say if this is a petrol or diesel? However, 2300 is not many RPM for either, you should hit 4000+ through the lower gears fairly frequently to keep the "Cat" or DPF, whatever, blown clean. If there are no fault warning lamps on, my initial thought is that you have a blocked exhaust. Or at the other end, the air filter may be blocked with debris. Any tyre/ exhaust place can check this for you, by revving the motor and seeing if the tailpipe is blowing enough gas out, and lifting the top off the filter box. If the exhaust is clear, you may need to get some diagnostic checks done in case the check engine bulb has blown, and the engine is actually running in "Limp home" mode.