So I have a 1999 A4 1.8t with a surging issue.
It idles just fine and drives at highway speeds just fine.
Driving it slow through the neighborhood the RPM's fluctuate and the car surges all over the place.
I'm thinking possibly a vaccuum leak, but could it be a transmission problem.
The CEL is not on so I don't think it's throwing any codes unless it is throwing a hidden code.

Anyone have any ideas?

 

Hook up a reader and see if there are any non-CEL codes. Start there.

 

Ditto. There may be a saved CEL in the system. Check there first and let us know.

 

I call spark plugs or coil packs.

 

I don't have a VAG-Com but I checked yesterday with my OBDII scanner and found no codes. I did spark plugs and coil packs last year so I doubt that would be the cause.