I recently spent a little time replacing the timing belt, water pump, spark plugs, filters, oil....all that stuff in my 03 RS 6. It's just now at 95k miles, decided to show it a little love.
Now, when I back it out of the garage, especially in the morning, it shudders and shakes, with RPMs dropping a couple of hundred and then making it right back up to normal. It doesn't do this while driving, and rarely while in neutral. It was spitting out the codes for running lean on both banks, no other codes. I don't have VAGCom yet, so no info there. I figured I might have gotten both MAFs dirty when I had the intake off, so I took it back off and sprayed them with MAF cleaner. Codes are clear, and have been for about a good 20 miles of driving, but the rough reverse is still happening.
I did disconnect a few rubber hoses to get better access to the coil packs, so it's possible that one of those isn't connected back tight, but I'm not entirely sure they're vacuum lines, probably, but I can't really find anything that labels what I'm looking at in this engine.
The only other thing I can think of, is maybe the whole intake isn't quite properly mounted, but it's very difficult to tell, since it mounts up on top of the engine, with the intakes themselves going vertical from the engine to the air filter box. Tough to tell, it bolts on tight.

Any ideas?

 

mine did this, it was a leaking intake manifold gasket. caused lean mix. esp when it was cold outside, all that plastic shrinks.

 

Been awhile since I've been on here. Yeah, the intake wasn't seated just right. Next time it comes off I'll make sure to have new gaskets to keep that from happening again.
On a different note, I was under the car yesterday replacing the fuel filter. Pretty easy to do, just annoying messing around with the single use hose clamps. But I did manage to break the external fuel pump electrical connector right off when I was strapping it back into its place at the end of the job. It's maybe a quarter inch of plastic with two copper strips going into the pump from the electrical connection. I didn't even realize I'd done it until I tried starting the car. After the fuel system got primed it would start and idle just fine for about 20 seconds and then bog down and die.
Can't wait to call the dealership and see what a new pump will cost me to order. From what it sounds like it'll be around $800.