eeeeccchhhh, first "bad" beer after primary

I brewed up a partial mash porter two weeks ago, and got caught up in some stuff in the mean time so I havn't had time to rack it. So it was in primary for 15 days. I havn't been using a secondary on these dark ales, so i wasn't too worried about it.

I racked it to the keg tonight, and pulled a sample. It seemed a little high F.G. at 1.018 and had a horrible tangy taste. I know, I know... just let it be for awhile right? that is the plan now. I hit it with some co2 and will leave it be for a couple of weeks in the corny.

There was an incredible amount of trub in the bottom of the fermenter. I think I picked up some while racking, but managed to leave most of it behind.

How long should I leave this at room temp??

3 weeks or so I would go for just for aging time. what was your OG/ recipe for a FG that high.

here is the recipe, I mispoke in my origianl thread this is an extract plus steeping grains not a partial mash. anyway, I came in at 1.064 because I was ended up about 1/2 gallon short after a full boil.

7 lbs. AMBER MALT EXTRACT
1 lb. SPECIALTY GRAINS
2 oz. HALLERTAUER HOPS (boil)
1 oz. FUGGLE HOPS (aroma)