That'* your boost control solenoid. It doesn't take long for the foam filter to crumble away. It'* not a problem. This is a short description of how it works.
Under most conditions, the PCM commands the boost control solenoid to operate at a 100 percent duty cycle (ON) to allow full boost pressure upon demand. However, if reverse gear is selected or the PCM detects rapid deceleration or engine load is extremely high, reduced boost pressure is desired. Under these conditions, the PCM commands the boost control solenoid to operate at a 0 percent duty cycle (OFF), which opens the bypass valve. With the Bypass valve open, boost pressure is reduced by recirculating intake air back through the supercharger inlet.
I'm surprised that with the nuts to the throttle body being that loose that spraying around there didn't change anything. That would cause quite a vacuum leak, and would allow unmetered by the MAF air into the engine. That could have been your problem.
Your coolant leak is a mystery. There isn't much back there where you're describing that would normally leak. I suppose it could be leaking from the knock sensor, or freeze plugs, but I believe that would be unusual.
Black 2000 SSEi, Silverstar Headlights, Angel Eyes fogs, 3rd brake light overlay, hi-flo cat, drilled 180 degree thermostat, Intense FWI, PCM, shift kit, and 3.4 Pulley. Solid front mount.