Chrysler Repair: 06 Town and Country : Steady speed miss, crankshaft sensor, shifting into overdrive

Question
QUESTION: Hello Roland,
I have an 06' Town and Country with the 3.8 engine and 73,000 miles. There is a very noticeable miss, buck, jerk at a steady speed between 40-50 mph only and occurs after the transmission has shifted into overdrive. If you accelerate or decelerate even slightly the symptoms disappear immediately. No computer codes are present. Have cleaned the throttle body and injectors, changed the plugs, wires, both O2 sensors, crankshaft sensor, TPS, ignition coil, and idle control valve. Runs great all other times. Any ideas? Thank you.

ANSWER: Hi Rennie,
That behavior is a new one on me. Is it possible to choose a gear shifter position which prevents shifting into overdrive so that you can determing if there is still that behavior at the same speed or a proportionately slower speed when you stay in 3rd gear? If so, is the behavior apparently rpm specific or mph specific. Without codes it is difficult to pin point a cause for such behavior. Let me know what happens in 3rd gear only, and also keep checking for fault codes. If it doesn't happen in 3rd gear but at the same rpm, then one would suspect something to do with the transmission. If it also happens in 3rd gear but at the same rpm the engine might be suspect, if at the same mph then the drivetrain may be the problem.
Roland

---------- FOLLOW-UP ----------

QUESTION: Thanks Roland. In 3rd gear the symptoms are still there only between 40-50 mph so it is definately a mph and not an rpm issue.

Answer
Hi Rennie,
That would lead me to suggest that it could be an issue with something related to the path between the output of the transmission and the road: a cv-joint on one of the half-shafts (check the rubber boots on the four cv's to see if any are torn), a tire or wheel that is out of round or off-balance (check balance, radial runout, bent wheel, consider match-mount of tire to wheel, etc.). Such vibration that you are experiencing may not have anything to do with the engine or transmission. If this were the case and you can pinpoint the cause it may not be an expensive 'fix' compared to the engine/transmission, so I would at least look there first.
Roland