92 Tbird Tranny Shutter

I need some help with a tranny prob. A few years ago my 92 Tbird tranny started shuttering while shifting. After a couple weeks a neighbor told me that a washer on the linkage cable had disintegrated and he replaced it with a bronzed one. The tranny shifted smooth for about a week but then the problem came back. I figured that driving it with the shutter for so long just ate up the tranny as the fluid had heavy burn smells. Yesterday I replaced the tranny and converter but I still have the same shutter. What could be causing it if it's not the tranny/converter itself? One suggestion was that maybe the throttle positioning sensor may need replacing? Could the linkage cable be misadjusted? Please help!

Go here: www.tccoa.com/articles/tranny/index.html# and look at the link for adjusting the aod tv cable.