Maybe something wrong with your throttle cable adjustment? Limp mode is strictly mechanical, and requires more pedal travel before throttle actually opens. It also limits full throttle to about 2/3 of normal. You can see that with ignition OFF. Remove air filter housing and look down through the AMM while somebody depressing accelerator. If everything looks good, turn ignition ON and repeat the test. You should see full travel even without starting the engine. Don't use throttle cable or lever in the engine compartment to open throttle. That would put it in the limp home mode.