Apologies if this information is elsewhere, but I've searched amongst the many threads and feel that none of them match my problem exactly. Here goes.

Have a 2003 1.8t B6 with a CVT (Bummer, huh) with 84k

• Car starts fine and runs well. But after maybe 10min-20mins it starts to shake under load. The moment I take my foot off the gas, totally smooths out. Put the pedal back on the gas and it starts shaking again.
  
• The shaking varies at times. Sometimes its worse, sometimes its very little. Doesn't seem to be any rhyme or reason to this.
  
• It's most noticable between 40-70mph, but is still there at all other speeds.
  
• When I hit a bump at speed and the car is briefly lifted, the shaking disappears, but comes back when the car settles.
  
• Idle is rough until I disengage the transmission by putting it in neutral - then its super smooth.
  
• No CEL.
  
• Shaking doesn't change when going on a curve or a turn.

Any thoughts on the best way to trouble shoot this would be great. Anyone else experience these symptoms?

Thanks in advance for your help!

 

I've had shaking under power problems with 2 separate non-Audi's with very different causes. Disclaimer: I had both of these problems with small American trucks, so they could both be useless.
1st was a Universal joint. I'm not even sure the Quattros would use a similar joint (haven't had that problem with mine yet). But if you have FWD you wouldn't even have one.
2nd was actually the Catalytic converter. A piece of something had broken loose inside the cat, and at varying degrees of back-pressure it would clog up and cause the car to shake.