Our 2002 bounder motorhome was running fine before a fuel up, 20 minutes later it lost power and was pinging badly under acceleration or trying to maintain freeway speeds it would take a nosedive. Like it was going into limp mode (no check engine light) As long as I didn't give it more fuel it was ok. Just couldn't go freeway speeds and going up hills was nearly impossible. We added 2 cans of heet. (No octain boost available) Also added 20 gallons of super unleaded to the tank of regular unleaded. Just not sure what direction to go. Fuel filter, knock sensor, or? weather conditions were as follows: warm 80 degrees, blue skies traffic was moving at freeway speeds.