That EGR valve probably is not the correct valve for your engine please check:
http://www.autopartsgiant.com/CAT_FRAMEX.cfm
it looks like 214-1090 would be the correct part number.
I have had the same problem with my Bonneville & I have successfully cleaned & unstuck mine several times. But look for a good price on one & purchase one or find one at a local auto parts recycler.
It may take a few starts for your service engine light to go out after repair.
This is a typical problem with GM EGR valves, good luck