Shaking above 50 mph

I have a 2007 Nissan Altima V-6, manual transmission. When traveling above 50 MPH in either 5th or 6th gear, car will shake in the front end, but only while accelerating. When I remove foot from gas pedal, shaking stops. Tires are new and balanced. Motor mounts are secure. Shaking is evident whether accelerating in a straight path or while accelerating into a turn. Shaking is even more evident when I have adult passengers in the back seat.

Is this “shaking” like the engine is struggling or shaking like something is loose?

I assume the car has front wheel drive. Get the CV joints looked at.

The engine is not struggling. Shaking/vibration is felt through steering wheel and visually noticable in the center console when a coffee mug is sitting in it. shaking/vibration is most evident when accelerating up hills while you are already travleing above 50 MPH. But remove your foot from the gas and the shaking/vibration stops. Contributor below mentioned CV joints. With only 37,000 miles I would be surprised to see these go out so soon, but will have my mechanic inspect these this week.

Thank you and any other suggestions are much appreciated.