Question for you stickburning offset dudes

Hey Brethren- I built an offset a couple years ago out of a 55 gallon drum and used half of a 16 gallon drum for the firebox. Since my UDS and Akorn have all my cooking needs covered, I really never used the offset. I decided to give it a go yesterday as I had some oak and some meat and wanted to play with fire. I started a handful of charcoal, then added the oak to get things going. Yes this thing is leaky as hell and homemade, but I put a layer of firebrick in there under the cook grate(where the baffle/tuning plates would be) and surprisingly it held temp pretty well yesterday while doing the baby backs. Also ran a small water pan.
Here was the problem- SOOT! I was getting a nasty layer of soot all over inside the cooking chamber and of course the FOOD! Not that chunky stuff that falls off the walls from moisture(I've had that happen too) but this was a flat black color soot, like the soot you find on the chimney of an oil lamp or lid of a candle in a jar. Again, I was burning straight oak, and the smoke I was getting out the exhaust was not to my liking either-not thin blue but more blue/grey and cloudy. I know the fire was burning hot and had a good bed of coals to start the next piece of wood added... what do you think it could be? Bad wood? Poor airflow? Both? Thanks for any insights.

Thanks for all the replies. As for the condition of the wood, it was seasoned not green, but had been sitting for a while in my wood pile covered with a tarp. felt dry when I handled it, but could've had moisture inside... I don't know really. Next time I'll use fresh seasoned wood not stuff that's been sitting for a couple years and see how that does. As for the intake/exhaust issue, I'm really thinking there's not enough exhaust area to create enough flow. I even drilled a couple 2-1/2" holes at great level opposite the firebox to help. I took some photos but waiting for them to load because yahoo mail sucks LOL. I'll post pics when I can. Thanks again.