My girl friend has a 2004 honda civic sedan automatic d17a1.
When holding steady speed around 40 mph there is a shuttering and vibration coming from the transmission area. It seems as though this is the speed right where the torque converter is supposed to lock up, but it seems as though it is just shuttering instead. If you let off the throttle, give it more throttle, put in neutral or leave in drive3 (all of which will unlock the torque converter) The vibration/shutter goes away. Also at speeds above 45 or below 30 the problem does not exist. It seems as though there may be a sensor or solenoid that is disagreeing with the ecu programming and what results is the torque converter locks for a split second, then unlocks, then locks again and again and again for an almost infinite cycle until you let of the gas or give it gas.

The tires and axles have been inspected and are fine. I am waiting for a response for someone that is knowledgeable on this transmission.
Thank you for your time