I thought I saw an authoritive post in which someone did a failure analysis on a failed throttle body unit. He found that the failure was due to wearing away of the resistive material used in the potentiometer (a variable resistor), which electrically controls the throttle body. There is a "wiper" that moves across the potentiometer when you step on your accelerator pedal. Every time you step, it wipes across the surface of this resistive material. Over time, the material wears away, and voila - ETS failure.

If this is the case, then it has nothing to do with the stuff flowing through throttle body, since the potentiometer has no idea what kind of gas you are using. I suggest that your observation is just a coincidence, and the potentiometer material will shortly wear away so much that your throttle won't work at all.

Keep good walking shoes in the car.