IPA Flat after 4+ wks in bottle?....

I have an IPA that is currently entering week 5 in the bottle after two weeks primary and one in secondary. OG was 1.091 FG was 1.031, the beer tastes strong but REALLY SWEET AND YOUNG still. oh, and it is completely flat. I couldn't get a head even by pouring it extremely agressively.

there was a few problems in the mash-
one when attempting a rest at 158 F i stepped away to check ProMash and the temp hit 168 F.

also, fight at the end of the mash when i was mashing out i was attempting to move the Thermo from kettle one to kettle two and caught the edge of the pot and broke the thermo.

should i just ****-can the whole batch?
i'm a little afraid that the thermo has poisoned the yeast, but i have no way to know.
or is it the temp spike in the mash stopping conversion?
i did an iodine test that showed full conversion, so i'm really at a loss here.

another option would be to empty all the bottles into a corny and try forced carbonation.

i have only tried two bottles that were bottled at the end of the bottling, but i suspect that all will be equally as dissappointing.

Boil a cup of water and 1/2 cup of priming sugar. Cool and add a little yeast. Uncap, add a teasponnful of mix, re-cap. Wait two weeks.

I second David_42 suggestion. Only thing is I would use a different ale yeast, probably a dry type. Sounds like your yeast may have stalled before bottling. I have a similar problem with a 1.122 OG. FG doesn't want to go below 1.052 and too sweet. I used a high gravity yeast.

i am not trying to insult you, but did you remember to prime it when you bottled it?

-walker

Yes, i did prime with DME.

so by adding more yeast and priming sugar it will carbonate, will it keep fermenting too?

i opened one of the 22 oz. bottles today that were bottled first, it seemed to have a bit more carbonatoin but still no head.

What temperature have the bottles been stored at?

Sounds to me like you got a screw-up in the mash, no matter what your iodine said. Sounds like you've been left with a bunch of unfermentable sugars.