I've got a few "what is this" pictures.
 

thanks to a friend of mine for being the finger.

whats this plug?
1. http://img81.imageshack.us/img81/5949/dsc04685ac9.jpg

What vaccume line goes into here?
2. http://img244.imageshack.us/img244/3205/dsc04686mh9.jpg

What does this adjust?
3. http://img244.imageshack.us/img244/3813/dsc04687xr3.jpg

What's this thing off the header?
4. http://img402.imageshack.us/img402/1039/dsc04688gj2.jpg

1 EDIT: thought u were pointing at somthing else
2 i dunno
3 looks like you idle adjustment
4 is for the smog system

1) plug should go to a VSV ype valve ( I have 3 on mine, and you only show 2 on the cover)
2) should be going to either the EGR or the VSV that is missing
3) Air valve (don't remember what it's called) U should have to mess with it -- do you have air?
4) Coolant tube

is it running rough at all? I would at least block that missing tube part.

there is 3 on mine, and they are all plugged in, there is just that random plug unplugged.

there is like a blue one, grey one and brown one plugged in.

it runs real real rough.

my truck did have A/c at one time.

:lol: coolant flowing through the exhuast?? number three IS an idle adjustment.

1. Not connected to anything on mine as well. But it is a connector for a VSV.
2. Not sure I'll look at mine.
3. Idle up adjustment for AC
4. allows exhaust gas to go to the EGR circuit.

1. was your AC idle up vsv plug
2. Thats the pair valve, one of your vsvs should have a vacuum line going to
it, trace all the lines from your vsvs to the hard lines and see if one of those hard lines is missing a hose on its end.
3. that is your AC idle adjustment
4. emissions junk, for the pair valve

BTW if you have your original hood there should be a vacuum hose diagram
pasted on the underside of it.

4) is Secondary Air injection manifold and should go back to a resonator

Sorry 'bout that but right beside (or in front of it) is a "return coolant tube" that looks exactly like it (hooks up to the timing cover coolant).

pair- pulsed air injection resonator
I know the coolant line you are talking bout, forgot to hook it up once;)

his AC idle up VSV is connected, white connector, you can see the vacum lines running from the idle up adjuster screw to it.

#2 is your fuel pressure regulator, which should have a vacum hose that goes to a vsv on the rear top of your valve cover

SO STUPID!!!!!:bang: :bang: :bang: Now I have to go find my cat-o-nine-tail and thumb screws!!!:hillbill:man! I so should have seen that!

I was under the impression that #3 was the vacuum controlled idle booster for power steering and AC.
The idle adjustment is the straight slot screw just below the number three in the date on the photo #3