Hey dude, well it's good that your pump works. Most of the time I see the vacuum hose that comes of the back side of the valve is all rotted and leaking vacuum, if you have a vacuum gauge then put that on when you start your car up cold in the morning. I really hope that is just a broken hose, if you have vacuum signal and your pump is working then you might have clogged secondary air ports in the head, that would suck.
And to answer your question, the valve is easy to replace, two 10mm nuts and thats it. If you happen to have a vacuum pump then you could also pull vacuum on the valve to check for a blown diaphram.