MAT sensor has already been replaced and the new one verified via the WinALDL logs. But I appreciate the ideas. Keep them coming.

When you pull your injectors, you may want to try using GM's Top End cleaner on the injectors. I've used it on motorcycle carb jets and such and it works fantastic. It stinks like all hell so do it outside. The trick with this stuff is you heat it up with a torch in say, an iron ladle with the part (or part of the part) in it until it starts to a boil at which point you will see the gas/etc tarnish just float from the part part. Brown carb jets come out looking like shinny gold.

Oh yeah, the stuff is flammable so be ready with something cover the ladle now and then to put the flames out. Even so, it's works so darn good it's worth putting up with the flames an stink. One other issue, the stuff is about $10 a can, which is little steep but you can reuse for like forever.

I did bite the bullet and pull the fuel injectors today. Yuck!

I've only run around the block a few time but the six new injectors and replacing all the plastic vacuum lines with Rodney Dickman stainless steel seems to have done the trick.

I know its been sometime since this post was made, I just wanted to say thanks for the help, and updates. I am also getting a 86 back on the road that's been sitting for two years, and is idling funny when cold. I'll start with the injectors and work backwards!
Thanks again for all the detail,
Dave