Engine Smoking

[LayanRubr]

Ever since I bought my 5.0 it has been smoking. I got a lemon and it started smoking a week after I got it. It had a recent rebuild on it with the papers. Heres what my car does (see if anyone can help )

-on a cold crank it doesnt smoke but dies if i dont give it gas.
-on a warm crank it will smoke grey smoke, and a lot.
-under a heavy load the car can make a internal backfire (nocking?) and external backfire at shifts
-when shifting it can also get internal backfiring
-the car sips about a half a quart every month of oil
-the car seems to be running rich, ive shot 2 inches of flames and 20 feet smoke puffs when racing it

I'm thinking its the valve guides but it could be piston rings (the mechanic could of done it wrongly). I've gotten many theroies of why this smokes, just wanna see what you gus think. One other thng is the "dollar bill" test. You fold a dollar bill and place it at the tip of the exhaust about 2 minutes after crank and if it sucks it in its a valve guide problem apperently? On the right side it smokes more than the left and the same right side will suck in the dollar bill while the left doesnt. Whatca think?