I have a 2000 Elantra that so far has had no problems for the 18 months I have owned it. I have done all the maintenance on it...oil changes.....plugs. In the last three months it has developed a mild stumble when at stop lights........no real frequency to it......comes and goes. I checked all hoses and connections. I couldn't find anything.....and it never does it when I'm looking for it. Anyway, yesterday I was driving for the first time that day and it seemed like it went into second gear (auto) and stayed there and wouldn't shift up or down......I stop, turn it off to lift the hood.....start it back up to check fluis level.....it was fine and still clean......drive off, and it was as if nothing had ever happend. Could the idle stumble and the shifting problem be related?