Error Code 299-Loss of Power

Has anyone ever experienced a sudden loss of power issue with their Airstream Interstate? I have an 2011 AI with about 23,000 miles. A few weeks ago, while driving my AI to work, I experienced a sudden loss of power. Even when I steped on the accelerator pedal all the way, the AI could not accelerator past 40 mph. Then, the Engine Diagnostic Indicator came on. Based on what I read in the Sprinter's Manual, it appeared that the Sprinter has entered into the Limp Home Mode (LHM) so it could not accelerate over 40 mph. I continued to drive the AI to work and then I took the AI to an auto shop near my company. The owner was very nice and tried to find out the issue for me. He connected a diagnostic scan tool to a port under the steering wheel and got an error code of 299. He reset the error code and the Engine Diagnostic Indicator disappeared and the AI drove normal again. This was apparently a Mercedes-Benz Sprinter issue, so I took the Sprinter to the local Meredes-Benz dealer. However, they said that since the error code has been reset, they could not do anything. The Service Manager suggested me to bring the Sprinter back when the problem re-appeared. It has been about 5 weeks since I enountered that issue, but the problem did not re-appear. I am planning to take my family on a long road trip and is kind uncomfortable with this issue. I would greatly appreciate if anyone can provide their inputs on this. Thank you very much!