Lexus "shudders"

I have a 1995 LEXUS LS. Occasionally - usually at about 50-60 mph under a slight load such as going up an incline, if I have to quickly back off the gas, the car rather violently shudders - almost like there was a quick brake instead of going into coasting mode. It rarely happens at 30 or 70 and I can usually avoid the lurch if I can gently back off the accelerator. Have taken it to several shops to no avail. Any thoughts? Thanks

Have you taken it to a Lexus dealer? There could be a bulletin on it. Sounds like a transmission issue to me.