My car one day started to have a little rough idle and wanted to stall sometimes. I took it for a check at autozone and got code P0-401. Yesterday I arrived home after a 30 minute run and when I parked my car and leave it idling it suddently stall which was rare and I turn it on again and seconds after it stalled again. Turn it on for a 3rd time and didn't stall or had rough idle. Checked it again at autozone and got same code. I tried cleaning the valve with carb cleaner, saw a video on youtube on how to test an egr valve with a vacuum pump. Bought a vacuum pump and tested it un mounted the valve diaphragm moves to the open position when vacuum applied and holds vacuum for atleast 5 minutes which I tested it. Also tried testing it with the car on at operating temperature and it won't stall or try to stall as video says it should when valve is open in idle. So I proceeded to clean the passages both with carb cleaner. Tried doing the same thing after cleaning the passages with car on and it still won't stall or try to stall. I don't know what the problem could be. I already tried a lot of stuff and still same code. Should I replace the valve? Any help?