Older post so I'm not sure if you have already remedied the problem. Knowing that someone else drove the car with the kickdown linkage messed up, the first thing you need to do is drop the pan and see what kind of trash is in there.Driving that big heavy car with K.D.linkage way out will eat the friction surfaces on the bands and clutches and overheat the other related surfaces.Had a very similar issue a long time ago. Dropped pan/fluid,drained converter,checked both bands integrity,and adjusted both bands to factory specs.I did alsoswap the valve body out with another similar, known good unit because of all the trash that was floating around,plugging up all the small orfices. Refilled trans to the correct level (hot and in neutral not park). Checked kickdown linkage and drove it around for the next couple years as a grocery getter, luckily avoiding a rebuild. Not every situation turns out so well,so easily and inexpensive, but it is so worth the effort. I opted to swap out the valve body instead of trying to flush the original unit as I had several used units laying around and thought it would ensure that I wasn't experiencing a plugged up V.B. Hope this helps. Bill