Disconnect the battery,remove the I.A.C valve, be careful not to damage the gasket,there should be holes in it showing the valve inside,clean it out with 2+2, until all the black soot is gone,replace it back on the engine, then remove the air cleaner hose going to the intake,open the throttle plate and clean the soot out of there too,i use a rag soaked with 2+2 on a scewdriver,replace the hose,and reconnect the battery,it might run alittle rough till it relearns the new idle. try this hope it helps.
