I have a 1991 pickup 22re 4wd 5sp manual that is constantly misfiring and has a high idle that i cant adjust down. The screw on top of the throttle body is turned all the way down, the screw is all the way down for the idle stop and on the dashpot the screw is almost all the way down...it has no power and is lugging, i tried to adjust the ignition timing, i turned the distributor counterclockwise (viewed from the driver side) idle increased to 1600 and i could not get it to drop....any help is much appreciated