1999 zx2 frame vibration

Hi all,
I have a 99 escort zx2 with an A/T. I just recently redid the whole front end. Installed new struts, springs, mounts, ball joints, tie rod ends (inner and outer) wheel bearings and CV shafts. Got it aligned after all that work and now I have a vibration whenever I apply power, whether its upon acceleration or when I'm going up a hill. The vibration frequency increases with speed and feels more like a frame vibration than a steering vibration. Does not make any difference on turning or not. After I noticed the vibration I put my winter wheels on thinking maybe it was a misbalanced wheel but no change. And here is the kicker, if I jack the car up the vibration will go away for about 45 mins of driving time before it starts to fade back in. Checked all of my bolts for tightness and changed the CV shafts again. brought it to another shop who could not find the source. They double checked the alignment and its straight as can be. Could it possibly be a bad strut? I installed Monroe sensa-trac with all Monroe associated mounts and hardware. Any ideas?

Also just replaced motor mounts last year.