I have an '87 Si. the Green Tape on that Loom makes me think it's just plastic wire loom that came of the Coil Wires that go to the distributor. Right there in your picture that run along the top of the firewall, buy that little Solenoid which is just there to bump-up the idle speed when the A/C is turned on. The high Idle Speed I would think is from the Fast Idle Valve which is "mechanical" on these rather than "electrical" like on newer cars. The top of the FIV is right there in your picture also on the left. I'll wait and see if you're still checking this thread before going further. I guess this forum is a little "low on traffic". Been years since I've been here myself.
___________ 1987 CRX Si NH-94M Quartz Silver __________ If it's got wheels or tatas It's gonna consume time and money