Specifically, a 1993 Cavalier. At approximately. 37 mph with light load, the torque converter lockout rapidly goes in/out. The effect is like driving over cobblestones.
The mechanic I take the car to seems to be stumped. The problem arose just after I had the transmission rebuilt, and to say the least, I'm not a happy camper.
Any ideas? I understand it's not *that* unusual of a problem.