Shakes or Wobbles problem
1991 Chevy Suburban V8 Four Wheel Drive Automatic 148K miles
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My suburban has a regular and consistent viibration under any throttle application that is most noticable at about 45-50 MPH in overdrive. It is noticable under the lightest loads on a level road. As higher speeds I cannot feel anything. It has the 480LE trans. If you let off the throttle it goes away completely. I have rebuilt the TBI, new Dist, new coil, plugs, wires, MAP sensor all have mad no change. Also put on new tires..no change.

I am thinking it may be the torque convertor. I am not sure if it is locking up. What sort of RPM drop should I see? Any thoughts as where to look for the cure?