Trying to salvage a beer that got stuck in primary...

Around thanksgiving I made an IPA with an OG around 1.087 and 1lb of hops. It was going to be a beast. Pitched two packets of dry yeast and by the next morning it was haulin'. After about 5 days, all activity stopped. I suspected that it got too cold one night (I've had temp issues in the new place) and considered pitching more yeast. I waited a few weeks, just to see what might happen. After nearly a month in the bucket I took a gravity reading around 1.015. Lookin' good, right? No, seems it was false - more on that later. Anyhow, I put it in secondary for 2 weeks and it's totally dormant. Cool. The volume of yeast from the bottom of the primary was huge, so maybe it did just ferment really quickly.

Anyhow, I kegged and carbonated it. Taste seemed off. Very sweet, low alcohol. I drew another sample and let it sit out until it was room temp and flat. Measured about 1.050. Crap. That explains the sweetness, and works out to under 5%. It's pretty hoppy and around 120IBU. I'm not sure if I'll pitch it, or if there is something I can do to salvage it.

So, should I try to siphon this back to a carboy and pitch more yeast? Obviously, I'll give it a day or so to flatten and come back to fermenting temp.

The carbonation could give you an inaccurate reading due to the CO2 bubbles. What was your recipe? Perhaps you have some unfermentable sugars in there.

.035 off on your initial reading? Something seems wrong. I dont see how u could b that far off between readings.