'03 Passat Vibration while engine under load

2003 Passat 1.8T Wagon w/ 5-speed manual transmission:
Had the CV Joints replaced a week ago by non VW repair shop. Four days later while driving on I-5 from Seattle to LA I noticed vibrations while the engine was under load (accelerating). Vibrations got worse since, still only under load though. This happens in 2nd, 3rd, 4th and 5th gear, but not in first! I can feel the vibrations in the gas pedal, steering wheel - the whole car shakes...
Probably faulty axles? Seems to be hard to find the correct part for this model. I had a shop that replaced the pass side axle, but the problem was still there. Another mechanic through in the towel today...
What could the possible scenarios be? Why no vibration in first gear?
TIA, Theo

Hello, By now I hope you have an easy answer. This may sound strange , but the first place to look is electrical.
Go to a dark place. Open hood, cover lights with a thick blanket and run the engine. NOT IN AN ENCLOSED GARAGE FOLKS.
Look for a blue glow around your plug wiring. Pay extra attention to occasional crackling. Watch each plug wire for at least a minute. Even new cars can suffer a high tension miss. The harder you work the engine the more you will notice it.
Its possible that you have a slightly bent wheel. I would block the car up so that both front wheels can not touch the ground.
Start the engine put it in 3rd or 4th gear and carefully observe both spinning wheels. They should not wobble or bob up and down. There should be no noise from the brake rotors. Is one side vibrating? Let me know how you make out Allan