Lots of stuff here - first off, nothing should happen when you pull the vacuum line off the egr valve. The egr valve shouldn't be hooked directly to manifold vacuum - the line to the egr valve should come from the egr controller valve on the firewall. And the computer should be telling that control valve NOT to send vacuum to the egr valve at idle. That's because the egr valve isn't supposed to be open at idle or wide open throttle - only at part throttle.
As for adjusting the idle speed - technically, there is no 'adjustment' per se. The idle speed is set in the computer, and it uses the iab solenoid and timing changes to try and hold the idle at a pre-set level - about 675 rpm. So, if you haven't adjusted the throttle stop screw (look underneath the throttle body - you'll see it), then you likely have a vacuum leak if the idle speed is that high - very common on hci swaps. You'll need to solve all your vacuum leaks before you start trying to alter the idle speed. This is really important - you're just pissin' in the wind if you try to alter idle speed with vacuum leaks.
The screw referred to above is a throttle stop - it's there to keep the blade from closing too far and binding in the throttle body. However, many people refer to it as an idle adjustment screw. If everything is working correctly, opening it will only cause the computer to close off the iab a corresponding amount to try and bring the idle speed back down. It seems that some cars/computers are amenable to 'learning' a new idle speed as part of their adaptive strategy and some are not. Can't explain why that's the case - but some people are successful at setting new/higher idles, and some aren't.
So, if you want to give it a try, here are the steps. With the engine completely warm, and running, disconnect the iab solenoid. It's gonna try and stall, so be ready with a screw driver to turn the throttle stop so that you increase engine speed. Turn the stop until you get the speed you want. Shut the engine off. Check the tps voltage with engine off and warm - if it's less than 1.3V, leave it alone. If it's higher, loosen the screws and turn it so you get the voltage down below 1.3V - preferably into the .95V range. Turn the ignition off. Plug the IAB solenoid back in. Disconnect the ground lead on the battery and turn your headlights on to kill all voltage in the system. Leave it that way for several minutes to clear out the memory of the computer. Then crank it up, and drive it for a bit. The more you drive, theoretically, the more the computer will learn about your new set up, including your attempts at increasing the idle speed. If it works, great. If it doesn't, an alternative that will certainly work is using a chip to reset the idle speed. You can also recurve your wide open throttle ignition advance - which the hci will probably like.
Just know that unstable idle/stalling/surging/idle too high/idle too low is one of the most common side effects of changing induction components on the engine. There is no one solution that's guaranteed to work each time. This issue is probably the biggest single complaint/problem that people have to resolve when they mod these engines. Some get lucky and it works out quickly; others have chased it around never solving it. Good luck with it.
