just putting the air intake on my 3.0 back on and i can't get the old gasket off. I've scraped and scraped and the thing will not peel off. Can i just leave it on or does that surface need to be totally clean before putting it back on. thanks

 

I would make sure it all comes off, for sure or you may encounter leaks and you don't want them there. Also a pain to have to redo it if it doesn't seal right. I just did this and found a razor blade works the best for scraping the old material off, then brake cleaner on a rag to wipe any residue that was left.

 

permatex makes a gasket remover that you brush on and it allegedly loosens the stuff up.
I've had decent luck using single edge razor blade, but you have to be careful to not gouge the head. you could also try using a brass cupped brush on a drill. every few minutes reverse the direction of the drill 'cause the bristles will start to bend.