2007 Dodge Caravan Continuous High Idling Speed

I had Firestone diagnose the engine and "P0507" code came out. They traced that there are 2 vaccum ports open and another 1 which is capped. However, they could not recommend anything since they could not find the parts in their diagram. Also, they did not see any loose tubings that may have been disconnected from those ports. But, if you plug/cap one port, the idling speed goes to normal and if you plug the other one, the idling goes down and engine stops. They do not recommend just to plug them since they did not find anything loose connection and it did not show in their diagram. Please let me know if you can recommend something or plug one port is normal.