I'm keeping it as my last resort option, but really determined to find the solution.

You seem to be totally averse to adjusting the stop, but you are also taking a shotgun approach to this problem. You got to have a plan, man. Finding the EGR problem was only by accident. It was good to find it, but it was ancillary to the inital problem.

Get a manual. I don't have mine with me right now, but the throttle stop is set to some specific gap, using a feeler gauage. Then, set the TPS. Again, another quick and easy thing to do, again, it requires some feeler gauages.

Then, set the idle speed using the air bleed screw. Again, making sure the passage is clear. After that, pull the vaccuum canister purge line, plug it and then set the timing. Rechecking the idle speed and then the timing to make sure they are correct.

Once you are there, then you can start chasing the other gremlins. I think you have a combination of timing and idle speed issues to work out. The temp spike can easily be a function of timing on the 2.6. I would even suggest looking for other vaccuum leaks or bad vaccuum lines.

Finally, start dealing with the aux air valve. Check the lines. Heck, plug them and see how it runs. If it runs better (after being warm) then maybe the valve is bad. I do have to say, I have never heard of one going bad. I have had lines pop off or maybe they crack (massive vaccuum leak, instantly) but AFAIK, the valves are relatively bomb proof.

Good Luck,
Michael