92' Seville Problem?!

Hello everybody...... just have a question and was wondering if anyone out there would be able to help me. Every time I start my Seville up it will idle fine but when i shift into gear (drive or reverse) the idle would drop, then if I brake the car would idle real low and cut off on me. Just recently checked the codes and they are clear. Which leaves me ???? could it Be the Brake Booster?? If anyone has any info please let me know, would greatly Appreciate it......:frown:

Mt first thought would be that the idle speed control (ISC) motor is unplugged, misadjusted, or has failed.

Mt first thought would be that the idle speed control (ISC) motor is unplugged, misadjusted, or has failed.
Seconded, common failure.