HI
thanks for the detailed response. First, seafoam is a fuel/intake additive that many have used to help "de-carbon" the intake system - most have used the pcv or brake vacuum line to "suck in" the seafoam liquid. You then let it sit, engine off for 5-10 minutes to soak, and then fire it back up and smoke the neighborhood
I also have used it in a tank of gas for injector cleaning although I believe Berryman's Chemtool is more highly touted for that use.
To your solenoid. As Wiswind detailed, the circuit diagram ('96) shows 12V+ coming to the solenoid on the red line - hot when key in run. Then the brown line running to the PCM which provides ground. As he said, the PCM then must be providing "switched ground" if you will to control the solenoid. i.e. eliminate ground to de-power the solenoid, shut off vacuum and allow the IMRC's to spring to the open, high RPM position. As by your numbers, resistance to ground on the brown wire remained constant, even after 12 minutes, I believe you are still getting an "IMRC closed" signal from the PCM, as the brown wire should be "open, i.e. no ground" when the PCM signals the IMRC to the open position - high RPM. I can't really help but blame the solenoid in that situation as it seems to have a closed circuit (commanding vacuum on) yet opens anyway shutting off vacuum. I wonder if 12 min., while consistent is just arbitrarily the amount of time it takes for the solenoid to heat up enough to increase resistance to the point that there is no longer enough current flow to keep it open? Hopefully you will get some other opinions too. I know this stuff is frustrating.