After rebuilding my 700r4 as fitted to my 86 IROC, I still have the same problem, as in it will go in to 4th gear but at the slighest touch on the gas pedal it jumps back into 3rd ???
Any solutions gratefully received..........................

maybe your tv cable is not adjusted properly

Is this at high speeds or low speeds? I installed B&M's 4-3 kickdown kit ( http://www.bmracing.com ) to eliminate that 4-3 kickdown at high speeds. Now, at regular road speeds, when my car engages 4th, it won't kickdown unless I either (A) shift it manually, or (B) push the gas pedal down to the floor. I like it; it turned my 4th gear into a gear I can "use", and not just "cruise" in. (I shift it manually, by the way, to go from 4th to 3rd. This way I can pass someone slowly & gently, instead of speeding off!)