EEC-IV Code 15 help?

[dispatchrobb]

I'm working with '89 BII, rebuilt 2.9, rebuilt M5OD-R1, complete new exhaust, all new sensors, relays, 80 amp alt, and the Mark VIII cooling fan isolated through two seperate Golf Cart solenoids on manual switch for high and low.

Check engine light starting coming on for a few seconds and then goes off. Sometimes won't come back on for a few days, then only on for a few seconds. Recently it's been staying on a bit longer. Sometimes when it's on it runs totally rough, sometimes it's on and you don't even notice, idles within the normal range with the vaccum gauge, or sometimes a tiny bit up and down but not all over the place. No rhyme or reason to why or when the light is on, comes on whenever it feels like it, in no particular condition, and something different seems to happen when it comes on. The only code I get is the KOEO secondary code 15. O) No Keep Alive Memory power to PCM pin 1 or bad PCM (Memory Test Failure) (M) KAM (pin 1) was interrupted (was battery disconnected ?)
Batt was not disconnected. All wires I can tell are good with no cuts or grounding somewhere.

Is my computer going bad? Or is there a pin or something I can check to verify it's actually the computer or a bad wire? I've searched for the code 15 information, but all I seem to get is just what the code means. Any direction would be helpful. Thanks.

 

[dispatchrobb]

problem is getting worse. With no engine light sometimes it will run at high idle, sometimes when it's a cold start it runs low idle, then goes high, then oscillates or idles normal, sometimes the light is on and sometimes it's off when this is happening. I think after driving it for a while it runs normal. There's not one thing it does the same. All the sensors are new, and the only code it gives after I clear it and it comes back on is the 15 code. Sometimes when I shift and I'm off the gas it stays at a higher idle, sometimes I'll coast in neutral (behind some slowpoke in town) and it'll idle high and eventually come down after a few seconds.