with the throttle at rest, adjust the kickdown cable so there is a slight amount of slack in it, then try it and see how it shifts. It sounds like it is too tight and is pulling the lever too far too soon. Also check to make sure the kickdown lever on the tranny is not sticking, as that will cause this problem too.Had a similar problem with my 88 ram 50 sportcab, and also had the sticking lever on a 1991 dogkota (yes i spelled it that way on purpose) that the kickdown stuck until I installed a carb return spring on it.