I got a 2000 A6 2.7T (automatic) its chipped and today after playing around with the stereo cables, for some reason it started acting weird, some lights are on; ABS light, check oil light, esp light and check engine. After 5000rpm black smoke comes out of the exhaust and I cant go past 30km/h (in canada its km/h). I also bottomed out in the morning, which might have caused the exhaust to create black smoke.

Betcha thats what caused it, depending on how slow/fast you were going. also i would take that thing into a shop and make sure you got that chip on alright.

Thanx for input it ended being a loose intercooler pipe. After the pipe was replaced everything went back to normal.