The computer doesn't really need an idle sensor--it's watching engine speed anyway. There is a pressure switch on the power steering and some kind of tie-in from the aircon that tell the computer to raise the idle when those systems are under load, which might explain why Adam's aircon masked his idle issue.
Idle control is done by two valves. The Auxiliary Air Control valve (which the computer controls) is located under the back of the upper intake manifold. The Idle Air Control Valve, which lets air bypass the AAC for a higher idle when the engine is cold, sticks up behind the EGR and works kind of like an electric choke (moves a valve as it heats up, only instead of opening a choke, it closes an air passage). EF&EC-14 of the '95 manual has a picture and description of each. (It also shows the AAC and idle adjustment screw together and calls the pair something else, just to be confusing.)
The IACV is only open when cold, which is when your truck runs its worst, right? The idle control components do one thing, and that's feed air into the manifold, bypassing the throttle body. That air is supposed to come from the intake tube between the MAF and the throttle body, meaning it's gone through the MAF already, so the computer knows it's there (and knows to add fuel accordingly). If the idle control valves are drawing air that hasn't gone through the MAF--air getting into that feed pipe through a crack or a hole where a mouse chewed on it, maybe--the computer isn't seeing that air, and doesn't know to add fuel, so the engine will run lean. It would run leanest when the IACV is open (when it's cold). Once the IACV closes, the engine would idle better, but still a little lean from the lower volume of air going through the AAC valve (low idle). When your foot's on the gas, the AAC should be closed, and the engine should run closer to normal (though perhaps not perfect given that the leak that was supplying unmetered air to the idle controls might also send some the other way to the throttle body). So, yeah, I'd have a look at that air supply pipe.
As for the EGR, I haven't heard of any real benefit to deleting it unless the valve is buggered. Mine works, so I leave it alone, though I did scrape some carbon buildup out of it when I had the intake apart and test it just to see if it was working right.