Just a wild guess, if your throttle pedal type is connected to the floorboard vs. hanging down from overhead, then it's also possible your Transmission Position Sensor (TPS) wires are loose or broken or you just need to replace the TPS. You may also find your engine runs better after you address this.
... Never mind if your coach does not use this type of setup.
Limp mode and also be caused by too low of radiator coolant in your overflow reservoir. And the reasons for that will become obvious pretty soon. But while I am on this subject, this would be a good time for your shop person to test the ph in your radiator. Do you know if you use OAT type coolant or the other green SCA type? This is an important subject most RV owners pay no attention to.
I will look forward to finding out what caused your engine lights to come on? It could be 10's of other things. In the meantime, if you ever want to throw another $120 at your coach, I would recommend this ECM scanner off Amazon:
Note: This is the scanner I bought, but I see it is currently not available on Amazon. ...But, I think you can order any "J1939 scanner" in your price range and you will be able to read our ECM codes. Just be sure your ordered Scanner comes with the right connector type for your RV.