1999 Hyundai Accent fuel and engine problem

Engine Performance problem
1999 Hyundai Accent 4 cyl Automatic 83000 miles

every time I fill up my gas tank, the pump shuts of every 10-15 seconds and it can take 15 minutes to fill my tank. I've been told it is probably the purge control valve. Local parts stores are not sure what it is. Is it the same as a canister purge control valve? Is it fairly easy to replace? Also, when driving on the freeway yesterday, I suddenly lost power. The motor would rev but the car was not accellerating, almost like I was in neutral. I have had no previous problems and it is running fine today on all the small streets. What could be causing this? Any help appreciated