Cadillac Repair: idle problem, seville sts, letters and numbers

Question
1995 seville sts w/ northstar. When I start the car it jumps to about 3500 rpm. It will stay there unless I depress the brake then the rpm drops to normal and stays there if I keep my foot on the brake. While driving, the car will stall if I let up on the gas pedal at low speeds. The service engine soon light stays on.
Your help please
Thanks

Larry

Answer
Test for codes:

1. Ignition ON, Engine oFF.

2. Simultaneously push and hold for 2 seconds the OFF and WARMER buttons on the display panel.

3. Write down ALL the letters and numbers that appear and how m,any times they appear until the display stops and indicates .7.0.

4. Turn ignition OFF.

5. let me know what codes you get