[dgee]

what about cleaning the terminals and grounds again try adding an extra ground from motor to body. also it could be plugs i know you changed them but my friend had a pickup truck he changed plugs still had the shakes in the motor.took it to a shop they put it on the scope and it showed a couple of plugs were no good under load changed them and truck lost the shakes. just remember he had a v 8 thats 4 extra cylinder it just takes one bad plug on a four cylinder to make it run bad. also can you take off the hood and drive it till you get to 2500 rpm and see if you can see any arcing on the motor from the wires or the coil. .probably does sound like a good idea but you have done everthing else.