engine struggles when brakes applied

[jfranks2003]

Hi,
My car has 152,000 miles, its a 1991 delta 88 in pretty good condition. For about a month, after starting the car up with no problem, I'd shift into gear and the engine struggled a bit. After that it was fine, car drove like a dream.
Then, starting recently, sometimes when i hit the brakes to come to a stop the car shakes fairly hard, and the check engine light flickers on for a bit, then goes right off. A few times the car stalled completely, then started right back up. It doesn't always do this when i hit the brakes to stop, I'd say once every 5 times, and actually stalls once every 20 times.
Also, when the car is in park idleing, if i hit the brakes and hold em the engine idles at a lower speed. I replaced the vacuum hoses leading to the fuel pump, but I really can't think of what else it could be. Any ideas?

[jfranks2003]

just to update, i did the paperclip trick to see if the computer said anything was wrong. I got a 12 response, which isnt listed in the repair book i got, so I assume that means the computer can't find anything. Please help!!!