The EGR system is used to lower NOx (oxides of of nitrogen) emissions levels caused by high combustion temperatures. It does this by decreasing combustion temperature.
The main element of the system is an EGR valve operated by vacuum, and mounted on the intake manifold.The EGR valve feeds small amounts of exhaust gas back into the combustion chamber.
Sometime just working without enough vacuum, clean it could make it normal.
I think if change a new EGR may cost more than $100.