I'm not sure if you've got that EST on your rig or not. Haynes manual says that's only on V6 engines .

I must confess that I'm not real hip on the newer rigs, my experience is with the gen1 engines, I've got several shop manuals that I've been blessed to borrow and memorize... well, use on a semi-permanent basis.

What year is the truck ?

Is the ECM original to the truck ?

I seem to recall that you pulled a 2.3 and put the 2.6 in, is that right ?

From what I could tell in all yer pics, all the systems are identical to my 2.6, so these books should "tell all".

The shop manual for my truck says:

Turn off A/C.
Verify idle is 900 RPM.
Adjust timing to 12 BTDC.

That's it! No hoses to plug, nothing...
The Haynes manual says:

Basically the same thing.

Are you sure the throttle cable/body isn't sticking ?
Will it idle down if you manually push the throttle closed?

C/YA!
Jeff
'88 Trooper
2DR LWB 4ZE1 5SP
bone stock DD