What I have tried so far:  I think my ECM is causing the excessive drain.  There are 2 connectors on the ECM.  When I disconnect the smaller one, no change in amp draw.  When I disconnect the larger one amp draw goes away.  This is the one that powers the ECM from the battery.

I disconnected everything that the wires from the larger connector goes to through either the up-line connector (C455) for most of the wires, the oil pressure sender, fuel pump relay, disconnecting the TCC Control, E cell timer module, MAP Sensor, TPS, courtesy timer and all fuses.  Still have 0.5 amps.  I checked for voltage on the C455 connector after it was unpluged and I am getting some voltage on a couple wires which I do not think I should have.

Can my ECM be bad and causing the amp draw? 

It is possible here is a service buliten I found

Wish I could help on this one Jeff, but an electricl guru Im certainly NOT...see there, I can't even spell it.

The TSB that Bob provided will give you testing procedure and thus the final answer, as far as whether or not the ECM is the root cause. Hope so, anyway...

Plugged a remanufactured ECM I got from someone in today and my problem seemed to go away.  Only plugged the one connector in at this time but currently very little amp draw.  Will try to connect everything I removed back in later this week and see what happens.  I'll use the TSB as a starting point to measure the draw.  Hope I have it corrected as I'm at a loss as to where to go next if not.

Fingers crossed! 

It could be a problem with either the ECM or the PROM !!

I have not tried to start or run the car since the switch.  I just pulled the ECM, switched the Prom and plugged the one connector back in to the new ECM to see if I had any draw.  Still have quite a few things to hook back up to verify this resolved the issue.  Did not consider the PROM.  I am assuming once I start the car everything will still be ok (no draw) and the PROM will recover all the information needed.  Anything special I need to do since I pulled and switched the PROM?

The PROM(Programable Read Only Memory) simply contains the operational info/program for the system. No need to relearn anything on purpose, or do anything like that. The info is "burned" onto the PROM...it cannot be changed, or altered just by removing/replacing it...unless you bend some of the pins, or put it in the wrong way/backwards.....THEN you'll have a problem!
I've never seen/heard of a PROM causing a voltage drain...it's not really something that could do that, in itself. It's more likely some of the circuitry in the ECM, or a failed component that is causing the drain.
Still got me fingers crossed!

Putting the PROM in the wrong way is a REAL problem.  You will insteantly burn the PROM !!  Trust me!  I did it !!!  There is a way to test the circuitry of the ECM.  I have a friend who worked at the AC Delco Plant, here in Oak Creek Wisconsin, that Engineered the ECM.  I will try to pick his brain!!