I have a 1992 Efini FD. I was having starting/boost problems so I replaced the clutch, spark plugs, gaskets for the throttle body, elbow and IUM (Used metal gaskets) when I was replacing everything I found that the engine had the black vacuum box instead of solenoid rack indicating that it was at least a 96+ Engine, so using the diagram up on the forum I made sure all the vacuum lines were where they should be (They weren't) but after putting everything back together I found the car now has a rougher start then before, as well as an idle surge, it drops between 300-500rpm at idle, I tried adjusted the throttle but that didn't help, when I push on the intake elbow the rpm seems to normalize but when I stop the idle starts surging again. I took another look at the UIM gasket and it looks fine, is it possible i damaged the UIM somehow? Could I put Gasket sealer on the gasket to make a better seal? Here's video of what I am talking about.

 

Cant tell much from the videos. A typical reason for a loping/hunting idle is a vacuum leak at, or after, the throttle body. The fact that it improves when pushing on the intake elbow would seem to point toward a gasket issue rather than a leaking vacuum line etc. A gasket sealer shouldn't be necessary with a new metal gasket.