[V6-12v] More little problems

[Nathan Widmyer]

I was going home, going about 70 mph in a 65 mph on an interstate.  All
of the sudden, there seemed to be some sensor problem.  While I held the
pedal down, it would not go faster than 70 and it started to slow down.
The engine seemed to be working because I can slow down to 60, then
accelerate back and hit the limit again.  I pulled over and turned the
engine off and let it sit for a few minutes.  I started it up and
continued on and the problem didn't happen again for the 20 remaining
miles on my trip.  This happened again the next day going 50 in a 45.
In both instances, the rest of car was working fine.  I'm thinking that
it's one or more O2 sensors messing up, sending false signals to the ECU
and therefore limiting fuel delivery.  I think one or both catalytic
converters may be damaged thanks to the local roads and if I'm right,
the O2 sensors are in the exhaust near the cat's, the O2 sensors may
have gone bad.  Anyone BTDT?  I'll drive it to the local Audi dealership
to have them fix it and get it inspected in 2 weeks and thought I should
get any insight I can.  Thanks, Nathan.