Originally Posted by krystallbluea4

A coil is just a wound series of conductor coated in a varnish. If that varnish or connections on either end of that coil are weak there is the possibility that an intermittent connection problem can occur. Also also occurs in relays, speakers and other electrical devices prone to generate heat. You probably should rest easy as you have already replaced two of the originals. They were all manufactured to the same specs and installed at the same time also the coils on these cars are known for being crummy so it literally was only a matter of time. As far as what else to look for? First get yourself two new ignition coils, I'll gurantee that its money well spent and worries no more...

Originally Posted by krystallbluea4

Well it is an Audi so there really is no guarantees as I'm sure your aware. However on the plus side with all four changed (coils definitely seem to be the most common cause of problems as far as driveability is concerned with these cars) You will probably be fine until she has the kid and then I'm sure that something else seemingly menial on the car will fail and cause yet another round of stress. I just replaced all four of mine with oems and almost wishing they would fail again so i could justify upgrading them. Good luck. By the way did changing the other two solve the problem?