How could I tell if I had a broken motor mount on my car?

Recently my car has been very jerky at cruising speed when giving it a little gas or letting off the gas. Wondering if some kind of mount broke or if anyone had any ideas why.

 

What gear are you in when this happen.
If in first ,its going to do that.
But you could visually check for excessive engine movement,or get under the car and check the mounts .Put it on ramps and take a look.

 

you could always put it in gear, fully press the brake, and LIGHTLY tap the gas pedal with the hood open... if if looks like your engine is trying to jump out of the car, that's a pretty good sign that a mount is busted.

or you could visually check to see if they look ok.

 

If it looks like this:



It's broke. That happened to me last year.