Hi,
I have a 1999 TT 1.8 Quattro. It has recently been starting to misfire, and doesnt idle as smooth as it should. Just wondering where's best to start? My guess is spark plugs and coils?

 

You got it. First things first change out the spark plugs if they haven't been in the last 15k miles.

If the trouble persists find out what cylinder is getting the misfire and then swap out the troubled cylinders pack with one of the other 3 to see if the trouble follows the pack.

Those are the first steps to take IMO.

 

if its bad at idle, the packs should be fine. Just spend the $10 and change the plugs and make sure they are gapped correctly. The packs should misfire until you actually try to accelerate

 

how do i find out which cylinder is misfiring?

 

^if your misfiring youll throw a CEL... just scan the cell and it should tell you which cylinder it is...

 

sorry, you'll have to explain how that is done. never done that before. How do I scan the cell? where/what is the cell?

 

i had similar problems with my car an chaged the sparks an packs an still misfired. check all you pcv hoses an lines i had a crack in one of mine that was causing it once i fixed it the misfiring stopped.

 

cel=check engine light. Go to autozone or advanced auto parts and ask them to scan your car. They'll do it for free right on the spot. Buy new spark plugs while your there as well. Make sure you gap the new spark plugs correctly. It says the gap's on the sticky at the top of the forum.