'05 CDI transmission "shudder"

[ROLLGUY]

My recently acquired CDI is displaying a weird "shudder" right after it shifts. If I accelerate hard, it shifts fine and then starts to shudder when I let off the pedal. If I am accelerating or decelerating, it is fine. Only if it has a light throttle just to maintain speed, it shudders. It almost feels like a clutch that is slipping-grabbing-slipping-grabbing real fast. I am hoping it is something easy to fix, like a solenoid or something. I have plans to change the trans fluid and filter, but don't want to do it twice. Anyone have any ideas? I may try calling Marc at Sun Valley Mercedes Transmissions to get his opinion. Any ideas would be greatly appreciated. Thanks, Rich