Tuning probs on an LT1...

[Ketzer]

Helping a friend get his vehicle back running. It's been down for a year while he searched for someone honest to work on it. (Water pump puked on the opti and killed it... if you know about LT1s, this is too common.)
Here's the issue I'm having,
Starts up great, idles perfect, runs great. Once it's warm and goes to closed loop, it gets super fat at idle (and through the whole rpm) and starts to stumble. New MAF, new temp sensor, supposed new O2s. Fuel pressure is correct.

The biggest problem, I can't pull the codes from the 'puter... scan tool says it can't communicate. I'm sure that I have used a scan tool on this thing before . I'm at the point now of pulling the ECU and having it looked at, both for the codes and to have the programming looked at...

A quick history, this is a project I did 10 years ago and sold to the current owner 5 years ago. 96 LT1 in a 87 Astro. A father and son (in Texas, I think I remember) did the wiring and programming. Sent them the van harness and the LT1 harness and they sent back a single unit that plugged to the firewall, I could swear I have pulled codes from the van diag port before.

Any suggestions?

Jeff-