l am having trouble finding someone to read the engine codes for my '90 Suby.Went to Advance, Autozone, Napa and another local parts sales store here in St. Louis with no luck.Or is there an ''at home'' method you can use shorting out the OBD plug and checking the flashes, etc?Any info or links to sites that have the info is greatly appreciated.

Those parts stores have obdI l scanners only. Some might do obdI, but l have never seen one, and you apperantly have not either! lol.
That is pretty much how you do it. there are different methods for different vehicles, but here is a link posted by another guy a few days ago and l bookmarked.
http://troublecodes.net/Subaru/
It might take a bit of work if you have never done it before, but good luck.

Theres some matching unhooked connectors under dash. Plug each in individually and turn on the ignition and watch the flashes on the cluster. Look up the code in a shop manual or that keen website from the first post and it tells you the affected system, go from there.