I've got a th350 sitting behind a 4.3L v6 (how I received the car) and the th350 only has 10k miles on it after getting it rebuilt. Whenever I start driving up a hill with the pedal on just when you feel the resistance on the kickdown cable, the trans just starts shifting down then back up over and over again until I let off the throttle or push the pedal to fully engage the kick down. I've disconnected the kickdown cable and if I hold the throttle in just the right place about where I had it before I disconnected the cable, It still does it. Still I went after adjusting my kickdown cable just to make sure. I'm at a bit of a loss as to what's going on. I've got an adjustable modulator and wasn't sure if that would really affect anything and I played ith adjusting it a bit but couldn't get the trans to stop shifting up and down. Any of you have any ideas what I might be dealing with?