Will not idle down?

[74bronco2]

I have an 89 b2 2.9 recently my idle has set itself to 2200 rpm with what sounds like an erratic single droping cylinder. I have replaced rotor, cap, plugs,and wires, checked all vacume lines and electricle connectors and ethered the intake gaskets. I unplugging the idle air motor and it changes the rpms slightly, there is no check engine light. I dont know were to check next.

 

[IMenriched]

I have an 89 b2 2.9 recently my idle has set itself to 2200 rpm with what sounds like an erratic single droping cylinder. I have replaced rotor, cap, plugs,and wires, checked all vacume lines and electricle connectors and ethered the intake gaskets. I unplugging the idle air motor and it changes the rpms slightly, there is no check engine light. I dont know were to check next.

check the other vacuum ports on the upper intake for carbon crusting over them. as well as, the throttle plate.