My idle is at 1050 when at a stop with all accessories off and with the brake applied. So I have new ignition components (cap, rotor, plugs, wires) with only 300 or so miles on them. My ignition timing is at 10 btdc. My vaccuum, according to my boost gauge, is around 600 mmHg. I have checked the resistance of the isc valve and it checks out. I pulled off the plug for it and it goes up to 1500 and then it *used* to go down to 500 ish and then idle at around 7-800 then go back to 1050. Now when I pull the plug off the isc it goes up to 1500 then to 1000. I tried taking off the whole isc but couldn't get the four bolts off. Is this evident of the isc bad or something else?