First off, I would try and seek out a BJCP to sample to get more accurate feedback. Hopefully you have a local or ship to one of us. This should help distinguish polyphenol/tannin astringency vs bitterness. That said, based on your description, lingering/back of throat is harsh bitterness. Classic for Columbus if you ask me. Did you use Columbus in the successful beers? IMO NE IPA should not have any high coho hops nor boil additions.
This is along the lines of what I was thinking. Astringency and bitterness aren't usually the same thing. For NE IPA-style beers I usually just use a hop shot to get my bitterness, or whirlpool hot to get my IBU's there. And Columbus and Chinook are two hops I'd never use in this style.