Told along time ago that the idle air control valve needed to be replaced. I replaced it (old one was siezed), now it idles at 2500-3000 RPM. Grounded the blue/white test connection to close valve to set base idle but idle doesn't change. Capped hose for idle control valve and idle returns to base idle. Wiring continuity checks good, resistance on (new) idle control valve checks good. Any suggestions? I think its posessed!