Carbon build up can cause them to stick, I'd consider getting some carb cleaner, and a new EGR gasket, then clean the EGR'* pintle, and area around the pintle, making sure not to get any of the carb cleaner up inside where the electrons are.
When you remove it use something to press in on the pintle, see if it moves in and out freely.
When you clean it, and out it back, clear the codes and drive it a while, if the code goes away you saved yourself some money.
I tried to find a good video on how to clean it, but all I could find was this, hopefully it helps.
2006 Pontiac Grand Prix GT with SC
1996 Buick Park Ave NA