I just bought a 2003 A4 quattro 1.8t about a month ago and it has started to hesitate when accelerating the last two days. I notice it most at low speeds, when I push the gas nothing happens for a second, when I release it and press it again the engine then picks up. I added a fuel injector cleaner additive to the gas and it hasn't helped. Does anyone have any ideas?

 

Check engine light?

Could be lots of things.. Vacuum leaks, maf, pedal sensor

 

I second codes / whether or not there is a CEL present.

I once had a 2000 Explorer that had similar issues that were really present when going uphill, but no so much on level surfaces. Turns out it was a bad spark plug. After replacing the spark plug numerous times, it turned out it was a cracked cylinder head. Thank god for my warranty on that job. I doubt it could be a cracked cylinder head, though. I have yet to hear about an Audi having that issue on these forums since I've been a member.