Cadillac Repair: Transmission problem?, torque convertor, tcc solenoid

Question
Recently purchased a 95 Cadillac Sedan Deville with the 4.9 liter.  148,000 miles.  Service records indicate transmission was rebuilt at 145,000.   

When driving above 35mph the car seems to feel like it's clunking when pressing on the gas after letting up.  Kinda feels like when you have a bad U-joint on a RWD car, but this is FWD!.  Also when in 4th gear between 45-55mph there is a slight vibrating hesetation type feeling and lack of power, like it's shifted into overdrive to soon, but it hasn't!  Kinda feels like a bad torque convertor, but I'm guessing that was problably replaced at rebuild, but maybe not?  

Answer
Could be that they forgot to tighten the torque converter bolts.

could be a faulty CV-joint in one of the front axles.

Could be a TCC solenoid that they did not replace.

You need to have a tech drive it as the diagnosis would go by the FEEL of the vehicle while driving it.