loss of power "check engine light on

Try changing or checking the fuel filter, fuel pump.Brick

In the old days to much power going up a hill (floor board and don't let up) you could "float the valves" causing a sudden loss of power from over revving the engine hopefully without doing major damage.

In today's engines with all the computer controls I doubt you could over rev an engine but what code would show up would be dependent on what shut the engine down if any code.

In the future you might try backing off slightly on the throttle before over revving if that's what happened.

Mine did it once on fancy gap , va raining and climbing the mountain. Shut it off, restarted it and light was on but power was restored and got home OK about 60 miles. I put an obd ll scanner on it and it said mas sensor detected lean fuel mixture, replace it. I cleared the codes and never had the problem again.

Sometimes it's just a matter of disconnecting the battery, waiting a few minutes (to clear any system capacitors)and then hooking the battery back up. What happens is you basically "reboot" the engines computer. Same type of problem and repair that occasionally happens to your home computer and many other modern electrical devices. I used to have to "reboot" my late wife's Mercedes about every six months when the power windows and mirrors would stop working. I should've replaced the computer chip but I was too cheap and it was a non-critical easily-solved problem.

Steve

The last time this happened to my SIL it was a mas air sensor problem. The motor was like in a limp mode and the check engine light on. We were in high mountains at the time.

Sounds like a problem the throttle position sensor. It could have a loose connector.OBD II codes

This probably is not related but we had a problem with our 2011 Suburban where the engine computer and the transmission computer stopped communicating and we had to limp to the dealer at 35 mph. They diagnosed the problem and the solution was to shut off the engine and let the computers reset themselves. When that happened everything worked find again and have had no problem since last February.
Just goes to show there is some `stuff' going on with these complex machines that we have do idea about.

Here is a site that might shed some light on your problem for OBD CODE p2135. You might google the other code
OBD CODE P2135

CODE PO120

Many times a code wont be the actual part as the code can refer to a system or circuit. A common one that I have fixed a few times is O2 sensor codes. Its not the O2 sensor, its dirty fuse connections for the heated side of the O2 circuit. Ecm sees a false resistance and sets a code.


http://www.justanswer.com/chevy/234yx-p2135-pedal-position-switch-a-b-voltage-connection-error.html

http://repairpal.com/obd-ii-code-p0120

Sounds like the techs are taking the usual throw parts at a problem since the customer is footing the bill. The 8.1 engine does have a rev/speed limiter that will shut things down if your speed exceeds a certain speed or your engine rpm's exceed a certain rpm. The exact limit is programmed in to your electronic control module when the engine is set up for your coach. When this happens, you will get a check engine light but after you shut the engine off and restart it, the check engine light will be off. On my coach the speed is limited to 78 MPH and I think the RPM is limited to around 4500. I've hit the speed limit shut down but never gotten to the RPM limit.