Ok so I have a 1997 A6 quattro Avant 2.8 12V with 85.xxx miles (timing belt changed at 70k) and it has been randomly stalling on me when the car idles.

The first time this happened to me was a week ago and it happened after driving the car for about 10 minutes. I was sitting at a LONG red light and after about 2 mins with the car in drive and my foot on the brake I felt the brake depress and heard the engine die. I turned the key into the off position, put the car in park, started her back up and off I went (Straight home lol).

When I got home I turned my car off and let it sit for 30-40 mins while I went on my computer to try and find some answers to my problem. After not finding anything I came back to my car and turned it on to see if it would idle. It would only idle for 30 seconds then die. I checked my car with a cheap cost co diagnostics tool I have...No error codes were found. So thinking that the diagnostics tool might not be able to read whatever codes I have, I decided to go to a auto parts store close by and see if their tool would pick up anything. No luck..No error codes found.

The next day I have my dad come over and take a look at the car. To my and my fathers surprise when I start up the car it idles just fine lol. I drive around with my dad for 30 mins or so and then try to get the car to do the problem again..no such luck, it runs like a champ.

Fast forward to today and its dejavu all over again. Driving around for 20 mins or so...car is doing just fine and then I get to another LONG red light and BAM! the car dies. O and ive been driving the car since it first happened and the car has been doing just fine.

Any ideas on what might be the problem? I'm thinking it might be a fuel pump/fuel filter issue but my dad thinks its something electrical. All imput is much appreciated.

 

Typical things to check are the idle speed control valve, EGR valve, radiator fans, vacuum hoses, plugged valve cover vent screens, changeover valve vacuum actuator, etc.
So, look for broken vaccum hoses, which may be making a hissing noise.
Do the radiator fans turn on when the engine is very hot and idling.
Connect a small hand held vacuum pump to the EGR valve. With the engine idling, the vacuum pump will cause the engine to die when the EGR valve is opened. If it does not, then the EGR valve passage may be plugged with carbon.
The idle control valve may need cleaning with throttle body cleaner.
There are many causes for stalling.