I am a new owner of a 2000 A6 2.7 and am loving the car so far. I searched extensively through previous threads, but couldn't find this exact issue..

The issue I have is this:
The car has a small lag in acceleration in any gear. When I first shift into a gear and then hit the gas, it pulls strong and I hear a nice whoosh from the turbos. It seems to pull hard for 1-3 seconds or approximately 1000-2500 rpms before losing some power for 1-3 seconds and then resuming a hard pull again.

Or to put it another way:
1000-3000 rpm - Strong and smooth acceleration
3000-4500 rpm - hesitating, jerky, slower acceleration
4500-5500 rpm - Strong acceleration

I'm not 100% sure the hesitation is tied directly to certain rpm ranges, as the timing of the hesitation seems to vary.

Background on car:
Manual transmission, 153,000 miles
Bought 1 month ago. No service history. Previous owner said the car is chipped, but have not been able to confirm. I don't know if timing chain/belt has been replaced.
I replaced oil/filter and spark plugs
Car drives awesome besides this issue.
CEL is not illuminated and no codes found with my scanner.

Any ideas would be greatly appreciated.

 

I have the same car, minus the hesitation. Start with the "easy" stuff if not throwing any codes. Air filter & fuel filter.
At 153K miles, I sure hope the TB has been changed, otherwise you're on borrowed time.

 

I did clean the K&N air filter in the first week I had the car. Fuel filter is a good idea. I'll probably do that in the next day or two.
Ya, I'm hoping the Timing Belt has been changed. I'm thinking it would be quite unlikely for the car to make it this far without that being changed, but I can't think of any way of verifying whether it has or not.

 

I changed the fuel filter. That didn't seem to make a difference though.
I put some sea foam in today. Thinking maybe cleaning the injectors off a bit might help.

Any other ideas?

 

I believe faulty EGT sensors would throw a soft code so it won't produce a check engine light. If they are faulty they will essentially cut power by causing your engine to run rich (This is known as 'limp mode' by us here on the forums). This is a common issue on the 2.7T as the EGT sensors have solder points that will eventually give out from the constant vibrations of the engine, and at 13 years of age, I'm sure they've had their fair share of vibrations.

 

Awesome, thanks for the info Nebuchadnezzar. That sounds like it could be it. I'll look into the EGT sensors when I have time and then post an update if I figure anything out.