Car Bucking?
 

I am just starting to have trouble with my car bucking/giving a violent jolt. I've felt this a handful of times, twice while braking and another time or two while just driving. After the buck, it almost feels like the car is "breathing hard" or maybe about to stall (though I've never experienced a car stalling so I'm not quite sure what that is like).

I own a 2007 2.5L Jetta, with 28,100 miles on it. I've read that the ignition coil can cause similiar problems, and did have these replaced about a year ago after a recall went out.

VW is happy to see if the ignition coil is still faulty/causing issues, but if not, I'll owe $138 for the diagnostic tests. Since I'm a student, I'm hoping to do some more research first. Would love some opinions on what could be causing the issue, whether it's possible to do any kind of diagnostics myself, and would also love any online resources you could point me to.

As more background, I had a 27 point inspection done on my car in late November. All checked out fine and I then drove cross country. Only other issue I have now (and that I've ever had), is my brakes are squeaking. Assume it's just the brake pads which I made an appointment to have fixed.

Thank you!
Kate