Open another, all UDS's are unique in how they get to temp and hold that temp. Yours is just wonky.
Also, when you put the meat on, it can soak up the heat for a while, and give you lower temps for a bit.
Is your basket off the bottom of the barrel? air circulation is key to maintaining and keeping temp. Also, that sounds a bit small for a fire basket. Further more if you kept the small holes in it, cut them out bigger.
My UDS gets condensation on the lid also, i dont bother with it, it doesnt change anything, or mean anything is wrong. A UDS is naturally a moist environment, which is part of its beauty.
Put strips of rolled tin foil into the channel, aka the foil gasket. Use the clamp if you have it also.