[78-911SC]

I'm having a problem with my 78 3.0 idle after warm up. Checked all vacuum lines and they are all good. I now have the idle completlely closed with the timing retarded so that the idle stays about 1000-1150 RPM after warm up. I removed the air filter and pulled down on the sensor plate and the idle came down which makes me think that if I could adjust the sensor plate(which I tried to do from in the air box but nothing) that I could open the idle adjustment screw and advance the timing. Should I continue with this thinking and remove the intake air boot and try to center the plate and make an adjustment or could I do a fuel adjustment and richen to lower the idle?