New to Audis...Again

[audirob44 at comcast.net]

Greetings All! 

After 5 years of driving BMW's and Japanese econoboxes, I've returned to driving Audi's.  I've just purchased a 1990 100 and an 1989 200 (both front wheel drive with automatics) and have some questions about them.

First the 100:
After driving on the highway for 10 minutes or so at sustained speeds above 50mph, the Check Engine light comes on and stays on.  Any thoughts?  The car has 176k on it and seems to have been well maintained.

The 200:
This car has 226k on it and has been very well maintained having been owned by the same guy since 1992.  The turbo will do 1.3 bar, and everything is tight.
When driving on the highway at about 60mph, the check engine light comes on, but will shut off immediately if I let off gas.  

Also, the blower motor is incredibly loud, and I would like to replace it.  Is this a big job, and where is it located?

The guy I bought this car from has amazing records on it and has rebuilt the tranny twice.  The last time at 180k.  What are some things I can do to extend the tranny life between rebuilds?

Finally, the car is hard to start when its cold, requireing that I crank it for about 10 seconds and hold the gas pedal part way down.  Once it starts, it runs rough for a few minute and will die if I let off the gas.


TIA for any advice, and its great to be back to these cars and this board.  It amazes me how many of the same people are still here.

Robert

1989 2ct
1990 1c
1989 1c (Dearly Departed 1st Audi)