Strange sound

Ok i have a 97 LHS. When the car is going a steady speed of 40-45mph (thats 65 - 70 kph) and then accelerated it makes a feeling and a noise. The feeling is sort of a vibration/shake that can be felt more in the front then in the back of the car. Now the noise is kind of a pulsating humming. Can someone please help me I've searched at least a dozen different forums and i can't find anything close to my problem. I did a general tune-up 1) cause i thought that would solve the problem and 2) cause it needed it and that didn't do anything. Thanks to the person that can answer this problem or direct me towards the answer.

you have something known as torque converter shudder. What that is when you reach around 40-45 MPH, there is a clutch inside of your torque converter that improves fuel economy by locking the converter up; making it one unit. That vibration & noise you experience is due to the fact that your transmission fluid is not properly formulated for higher mileage useage on your particular transmission. What you need to do, you'll have to go back to a Chrysler dealer, buy 5 quarts of Mopar ATF +4, drain your old transmission fluid and replace the gasket and filter and put the new fluid in. That should help significantly on how it feels when it reaches 40-45 MPH.

ok thanks a lot man i'm gonna try that out after the 4th.

Happy early 4th of July to everyone on here.