It is ancient technology with higher than stock timing levels that do not agree with today's crappy gas. I have one just like it in the garage, same part number. Hell I just noticed you're in tulsa. I'll be there in about three weeks if you need some help, it would keep me out of the casino for a little while.

I have another one or two chips for stock injectors I could bring but it's probably not the chip.
Some things that would help diagnose:
Do you have a scan tool and what are your BLM #s reading?
Define horrible. Is it 2 or 12 mpg?
Write down the numbers off the injectors and post them here. Also note any identifying marks (colored stripes/bands or colored tops). Bigger injectors with that chip (which is for stock injectors) would make it run piggy rich.
Does it have an adjustable fuel pressure regulator? And can you get a fuel pressure reading for us? Should be low 40's at idle with the vac line unhooked from it.
Can you smell fuel out the exhaust?
Is your trans getting into OD for sure and is the torque converter locking?
This could be just the beginning if something doesn't jump out with the above tests.
Also you should either have this thread moved to general tech or start a new thread there. It will get more attention there.
hope this helps. And I am serious about stopping by the hard rock hotel down there in less than a month. I could bring my scan tool/laptop and a fuel pressure gauge and some other stuff I've got laying around. Might be able to locate the problem.