My 89 260E has develope a problem of some sort. Yesterday I drove from Las Vegas to Albuquerque. Running at 75mph most of the way, I filled the tank up at a Chevon in Flagstaff. After about a half hour or so the power started to go down hill, the economy needle went into the red and the rpms increased. On a flate part of the road it seemed fine, going up hill major power lose. Gas milage went from into the hole also. I went to start her up this morning the the eco needle is going from the very begining of the red to the "middle" of the black. Going in reverse the needle jumps into the red and it also does this when I apply the brakes. Could the change in altitude have something to do with this? Anorther thing I have a question about, on the air fliter housing there is a hole in tthe middle of it. In the owner's manual it has a picture of the enigine with nothing in the hole. In a parts book that came with the car it shows a plug in it. Should it have a plug in it? Help this poor Air Force member out.