O.K., Here is my sad story
Purchased my 93 SSE about 6 mths ago. Had the SES light on at the time. Being brave or somewhat stupid, I thought it would be simple to deal with. I checked the codes myself and came back with a cam sensor, boost solenoid, EGR and quad drivers(wasn't sure which list of codes to use for my 93 at this point). Cleared the codes so I could start over, started and drove and the SES reset. Cam sensor and EGR. Replaced the cam sensor, cleared the codes. SES reset with EGR, quad driver and PCM.
Feeling beat, I took it to a local shop. They found a short in the wiring at the EGR replaced the maxi fuse and snet me on my way with no SES light. Two months later the SES returned. Having a 12mth/12,000 mile warranty on the local shops work I returned it to them and they eventually found a short in the wiring near the PS pump. Not sure of the code or circuit that was at fault. No SES, I'm happy again. One month later my SES is shining bright. Back to the local shop I go. After a full day with the car they gave up and recommended I see the dealer. Apparently, the EGR circuit again (code 55 and 56) but they could not find the fault. :? Local dealer quickly pointed at the EGR. The same one they had replaced for the previous owner 15 months earlier. I know it was 15 months cause I have the receipt and they would not honor the GM warranty. Saved my pennies and shopped for the best price on the golden nugget (EGR valve). Replaced the EGR, SES light out and then back in 5 miles. Next day 10 more miles and the light is out. Several hundred miles and the light is back (code 55). Ignored it for a day and the SES went away. Another couple hundred miles and it is back. Code 54 and 55 this time.

Shall I give up and just put some black electrical tape over the light? Any ideas? Is the EGR valve and circuit going to be the death of me?

I used to get an occasional EGR error code for the medium solenoid opening on my '92 SSE */c. I think it was code 54, but I'd have to check. In my case, I first removed and cleaned the valve and its 3 ports, but the error still occurred occasionally, always when the engine first reached 185 degrees or so. I then tightened the electrical connection fingers inside the connector on the top of the valve - I've only gotten the error once since then, and that was on a hot day and might have happened while going over big bump or something.

I can't comment about error code 56, though; that hasn't happened to mine.

I do get code 58 (Pass Key fuel enable circuit), though, and I've read that this affects other bonnies also, mostly the '92. In my case, there are no driveability symptoms. My '93 hasn't had either of these error codes.

I have some codes that occasionally come and go also. I have had the quad driver before but it never posed a problem. Right now I am dealing with an intermittant knock sensor code. I can't see that knock sensor, where the hell is it?

By the way, I had that pass key code before too. '92 ssei. I used some "deoxit" on the key contacts. Put some on the contacts and then insert it in the ignition a few times. After that I never had that code come up again.

the knock sensor is located on the firewall side of the engine, passenger side corner, below valve cover, near exhaust manifold. It has a single blue wire going to it.

Update
So the SES light is back out. Thanks jr's3800 for the code clarification. The Chilton manual I have is a little gray on those codes. I haven't had any driveability issues short of the "Shift point" post I had earlier which was just a question. Since replacing the EGR, the gas mileage has improved, but no other changes. I thought about tightening the connector pins. I'll give that a shot tomorrow. If fuddyduddy is out there or someone else has more ideas, I'm open. I'll take all of the free advice you guys are willing to give. Is there any way to actually verify if the ECM is the trouble?