So, I de-messed the area under the intake. No change in how the car runs (horrible cold start, lousy idle until warm), but I guess I didn't expect much, since I'd replaced all the hoses a year ago. It is easier to get the upper intake and throttle body off without that stupid coolant line, however.
I ended up putting the heater plate back on. My intake boot is stiff with age (and now partially torn) and I couldn't get the boot to line up correctly with the MAF box and the throttle body; I need to space the throttle body back out from the intake. I'm going to order a replacement boot, but I'm wondering if anyone else had that problem.