I got a 95 peterbuilt with a cummins m11 it's idling around 1000 which should be around 700 check my tps it showed good the idle increment/decrement won't work changed new switch tried to program ECM with new idle speed wouldn't accept it thinking it's ECM anyone have any idea

 

sounds like the pump is sucking air check fuel lines .

 

Doubt that... Did u try the engine postion sensor yet? Its down by the oil pump and air compressor. Also check the wires that do to the idle adjustment on the dashboard.

 

Any news?