A4 performance questions

[Simmonses@aol.com]

Hello fellow Audi people,
I am the owner of a 98 A4 1.8tQ stick, it has 17,000miles on it.
Since it was new I have always had the impression there was something wrong 
with the acceleration. Every trip to the dealer has been met with the same 
NFF readout from the "techs" and car's computer alike.
The problem I am having is an intermittent hesitancy when under hard 
acceleration, especially when the motor is cold. It feels like sometimes is 
as if there is a slight fuel blockage?
I am planning on chipping it as soon as the warranty is almost up, but I want 
to make sure it's running just right first.
Has anyone out there had similar experiences or have any ideas for me?

Peter S