Car shudders when accelerating uphill?

Have axles and wheel bearings checked. Also try manually holding the transmission in different gears to see if engine rpm has anything to do with it. Could be a trans issue or even an engine misfire that is most pronounced under load

Read the guides below, it might help

https://www.2carpros.com/articles/automatic-transmission-problems

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

It's impossible to diagnose things like that over a computer but to start the process, where do you feel the vibration, the seat, steering wheel, or entire car? If the steering wheel shakes, a worn inner cv joint housing is somewhat common. They will cause the steering wheel to vibrate when under load as in accelerating, and it will go away when cruising and coasting.

Vibrations felt in the seat are often due to a broken belt on a rear tire. Bent wheels will do that too. Broken tire belts that aren't real bad yet often are more noticeable on high-speed corners like on highway off-ramps.

If you feel the vibration when the car isn't even moving, that leaves out everything related to wheels, tires, and drive train. There's a misfire in the engine, the outer cast ring on the vibration damper has turned and is coming apart, or, on some engines, the balance shaft is out-of-time. That balance shaft doesn't usually get out-of-time on its own. That happens from being assembled improperly.

The first thing I would do is rotate the two right side wheels front to back, then drive it to see if it's the same. Then switch the two left wheels and drive it again. Wheels can get bent on older types of tire changers and unless the mechanic has reason to suspect that, he won't see it on the spin balancer.

The next course of action would be to use a dial indicator to measure "lateral runout" by spinning each wheel when it's off the ground. Some brand new wheels will have excessive runout that causes a shimmy. If you find one that's excessive, there are other things to check before condemning a wheel. While they're removed, rust and scale can break off and fall behind a disc brake rotor, or a piece or scale can get stuck between the wheel and hub. Either of those will cause that wheel to wobble but you often won't feel it under all conditions.

Please start a new question specific to your car. Be sure to list the engine size, and any other observations or clues such as WHAT vibrates, and at what speeds. Vibrations can be felt in the steering wheel, the brake pedal, and the seat / entire car body.

Has the front-end been aligned, lately? Does rotating the tires make any difference? Some makes and models, I've seen bad shocks cause a vibration.

If you took it to an alignment shop, what did they say about the vibration? If the alignment shop is at a loss, I'm not sure what to tell you?

Welcome to the forum, can you tell if it is tire or engine related? How long since a tune-up? Any codes?

It sounds like the engine is misfiring here is a guide to help.

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Please run down this guide and report back.

Check motor and tranny mounts