I'm getting a pretty major vibration with my car under load. If I'm cruising at hwy speed and maintaining speed, she cruises fine. When you mash on it and accelerate, the car gets a major vibration.

I just replaced the Pass side axle....checked all the mounts, etc. Any ideas?

 

If you've replaced one axle, then chances are the driver's side axle might be having issues as well. Check the mount for the intermediate shaft as well as the intermediate shaft bearings that are pressed into the mount (make sure everything is nice and tight) also, check the inner CV joint on your driver side axle. If it was a tire it would do it all the time so I don't think its that... My civic did exactly as you described and it was a bad inner CV joint.

 

Was the boot torn?

 

My boot personally was not torn, but a torn boot leads to dirt getting inside and grease getting out which speeds up the wear on the axle. If your boot is torn, you might as well replace the axle anyways because even if its not bad, it will be soon and you don't want that!

 

Axle.

If you used a cheapo from autozone then it is probably out of balance.

Get a decent set from raxles.com

Your problems will be solved.