Hey 90Vette. Congrats on passing emissions. I am in a very similar place as you as far as this tuning thing goes. Just passed emissions a week ago, tune is good enough to drive the truck but still has a long way to go, and I am still climbing the learning curve on TunerPro. I am excited to try out trimalyzer. Good find!

I am still learning so take with grain of salt, BUT, in response to your comment
"I was looking at my PE tables, and I realized that on the stock BIN for a '90 Corvette the PE AFR ranges from (assuming a realistic coolant temp) 9.96:1 at 3600 RPM to 13.25:1 at 1200 RPM. I've heard that 12.5:1 is usually ideal for making power, but the stock tune stays below 12:1 from 2800 RPM up. Why would GM have this so rich, and should I change it to 12.5:1?
I highly recommend that you read this article: http://www.diy-efi.org/gmecm/papers/tunetip.html

It is old school but still relevant. BIG takeaway is that the AFR settings in various tables are basically a LIE. They are just means to an end to get the ECU to operate in a manner that gives good results. So don't get too hung up on the specifics (like stock tune being below 12.1). It seems that what is important is that these numbers indicate a direction (leaner or richer) that the ECU will try to move the fueling towards. So in this case the stock tune is just telling the ECU to move richer above 2800 RPM.

Again, a highly recommended article. Many concepts in there that I will be applying towards my tune.

Hope this helps. Good luck and have fun!

AC