A few years back there was someone on Redpepperracing.com who was making up carbon fiber, and fiber glass copies of that part that goes in front of the hood, as the original is plastic and they fall apart after 25 years, a copy is going to be better then a used part because you would then just need to spend $10 on matched spray paint.
If the idle is to high first thing to check is that the warm air intake is intact, this is the tube that goes from the exhaust to the underside of the air cleaner housing's intake, if that tube is not there your engine will not run correctly, could run to lean and cause engine damage, also make sure that all the vacuum hoses are in good shape and replace any that have cracks or holes in them as one that is missing or damaged can also cause engine damage, although some people do pull them, or cap them off and don't notice the problem until the engine is fully warmed up, or the weather changes, those hoses make all the fine tuned adjustments that make your car run really well.
If you need a shop manual check out
This Link, it's a PDF file shop manual that covers the civic and crx's from 1984-'88 although some of the info in regards to trim level is a little confusing because it covers models from Europe.
Is this the CRX that was on Ebay a few weeks back?