Car shakes when under load Options

[FWD-3SGTE]

While driving, I'm experiencing a shaking when under load, more noticeable on the highway. Shake resembles tires that are out of balance but I just had an alignment done and the wheels balanced last week, no change. More throttle = more shaking.

It's quite odd.. Any ideas?

I just bought the car last month and I'm trying to work out the bugs to get it to ride better.

[Bitter]

Get under the car, grab the axle shaft, and try to shake it up down/left right inside the inner axle cup. It should have no lateral movement, if it does then the inner joint is worn and under load the axle is being pushed to one side which makes it wobble out of balance. It doesn't take much out of balance to shake pretty good considering at highway speed that axle shaft is 10lbs spinning at 4000 RPM.

Some in/out movement is normal on the inner axle joint btw. The outer axle joint should have little in/out and no lateral either, but the wear to check for in the outer is to hold the outer cup with one hand and try to twist the axle shaft. It should not have any rotational play or very little, if it has a lot then the outer is bad. Usually they'll click when turning when the outer is bad. The only symptom of a bad inner is shaking under load at higher speeds, unless they're really bad then they'll shake at lower speeds too.