Engine Vibrates at 70 MPH+
 

I recently replaced my cars engine 1994 E320E with a used engine under 40000 miles on it. After reinstalling everything the car start to vibrate at high speed. It looks like it bounces at 70+ mph. After the awhile when the engine reached its operating temperature the car has little rough idle when stopped in drive. I had the tires balanced and the vibration still there. I poured fuel injector cleaner into the gas tank and no change. Anybody knows what causes this vibration?

Get it up to 80 and then put it in neutral. If it's still vibrating, it ain't the motor.

Did you make sure the engine mounts are seated and bolted down properly?

I did the 80 mPH test and placed the gear in neutral. The vibration still there. It's not really vibrating. Its kinda jump a bit at high speed. The engine mounts are seated right and tight. Idon't know if its the tire is unbalanced but I return the car to Peep Boys to have the front tires balanced. One thing I did last time, one of the rear tire has hole on it so I inflated it with the tire inflator (liquid) in a presurized can. Will this affect the cars vibration?
Any more possible caused of vibration?
Thanks in advance.

Drive shaft/center bearing, trans mount, differential bushings, tires, wheels, tie rods, struts, rear suspension bushings, all those can cause vibration if not in good shape.

The engine itself is probably the least likely thing to cause vibration.

This.

Replace the rear tire with the sealant inside it. It's highly likely that is the source of the vibration. Best to run Michelin tires on MB automobiles because they are manufactured to high standards and are truly round.