My Caravan is a 4 cyl 2005 with 177.000 on it. This vehicle is in excellent shape for it's mileage, except for a recently developed problem. It seems to be trying to shift around sometimes, not every time I go out, just sometimes. Up on the Highway moving along at 60-65 it seems like it's trying to shift out of the highest gear (overdrive) and will even make an attempt to shift down lower. On secondary roads it also attempts to shift around, but feels more like something is holding it back. One other sympton is the idle of the engine is increased slightly, not real high, just slightly. Any help and/or advice would be great.