Jamb the gas pedal to the floor. Without it running, of course. Get under the car and check where in its travel the kickdown lever is on the transmission. If it is not ALL the way back as far as it will go, adjust it so that it is. There should be a threaded adjustment both under the car, as well as under the hood. Once you get the kickdown lever at the transmission all the way back as far as it will go with the gas pedal on the floor, drive the car. If it holds the gear out too long, readjust so that the lever does not get pushed all the way back. Keep working from there until you achieve both timely upshifts and so that it down shifts when the gas pedal is depressed hard. There is a procedure in the manual but this method has worked best for me.
