1989 Chevy Celebrity Engine Check Light

I have a 1989 Chevy Celeb is having a weird problem. I have done a search on the forums but have found anything similar to this.

When driving the speedo drops to 0 and then the Check Engine Light goes on. At this point it starts to run rough with little power. If I press on the brake while this is going on, the car sometimes (but not always) stalls out. I have gone through some basic troubleshooting, but still have not fixed the problem. It is a 2.5l 4 cylinder engine, automatic transmission.

Has anyone had similar problems like this? Any help would be greatly appreciated, I am running out of things to do.

Thanks in advance for any advice.

Have you been able to retrieve any trouble codes from computer since the check engine light is coming on?

Not yet. It's relatively new.

After messing around w/the speed sensor earlier today and cleaning the fuel injector some it cleared up for about an hour or so. Took the car for a couple drives and everything seemed good. On the way to a movie tonight the same symptoms started happening. Since it's midnight now and I work tomorrow I don't think this is really the best time to take a look at it :).

Again, thanks for any help. It's needed :)

Check the harness to the Ignition switch. As the contacts get old they can come loose. The switch may be bad, but I would check the plug before replacing anything. The clue is your hitting the brake and causing a change. The harness runs down the top of the steering column and then right above the brake pedal. Your hitting the brakes may be shaking this wire. I cannot think of anything under the hood that would cause this when you hit the brakes othe than a loose ground wire. Good Luck.

Thanks. I will definitely give this a try before hitting any place else up. Appreciate your help. <crosses fingers>

After going through pretty much everything, hooked up a reader and got a prom chip error. When talking to a mechanic he said he had only dealt w/that once before and that it was more than likely something w/the onboard computer. Swapped the computer out, working fine now. (Well, three days fine).