It's the bimetal valve... Whatever the hell that is. Two vac lines and screws into a coolant line/reservoir.

There was so much gas in the upper intake manifold. Pretty sure it was the cold start injector that was leaking after all. About to get it finished up.

 

Okay, I got it all put together. Then I jumpered the fuel test connector to check for leaks... Holy crap, one of the injectors sprayed fuel all over the place! It's leaking from the o-rings on new flamethrowers. Did I tighten down the rails too tight? How loose are the injectors supposed to be? FSM says that they should be able to rotate freely in the rails, with the rails torqued to 9 ft/lbs... that's nothing.

The injectors fit very snugly in the rails, even the one that's leaking. The o-rings look fine as well. I've got a test rig set up on it now with the UIM completely off, tomorrow morning I'll take another look after the gas I couldn't get to evaporates. Hopefully I can find out what's causing this leak, what a PITA.

Thanks for the help again guys.

 

Oh that is the little device that holds vacuum off of the EGR system until the engine warms up properly.

When you install the little grommets on the injectors its always good practice to use a little petroleum grease or just some clean engine oil on the rubber orings so they dont bind up.

 

Fixed it! I had to get bigger grommets and beefier o-rings that I borrowed from the 88 alltrac in the garage, but no leaks anymore. Starts right up! Drives great, seems more responsive and a tad more power according to the butt-dyno. I'm burning off spilled coolant, but no smoke and no fires as of yet, lol. (Knocks on wood.)

I believe the first replies here were correct about it being the cold-start injector, judging from all the gas in the intake manifold.
Thanks for the help and guidance and ideas, guys!