2004 c320 wagon with 60,000 miles was slightly bucking and moaning (light vibration) Took to tran shop, they replaced torque converter, solenoid, plate , etc.... totally fine for 2 months, then same prob. There was no antifreeze in trans fluid (common problem from what I have read), then same problems came back. They fixed again under warranty, but two weeks later problems came back. Could this problem be Transmission Control Unit related ? Help....thanks