Buying a 88 Suburban, is EGR valve necessary -or will it hurt motor if plugged up?

[OverRunWithSons]

I am the wife asking this question..... the Guy selling says the engine light will keep coming on, but this is just due to this EGR valve problem, that he has not fixed in years, and it runs better with it Plugged or not used (I forget what he said). When it was in use, it keep stalling and jerking at traffic lights, etc. No problems after unhooking. I've been reading about these, they sound like a real hassle for some, always getting clogged, plugged with problems. Is it best to just leave it the way it is--not replacing it --not in use. What is purpose of this valve, and if it will not further hurt the vehicle, why do I need it? Thank you.