Cobra sounds like crap/smoke etc. help

My 01 Cobra that I just bought last week has developed a problem. This morning when I started it up a puff of white smoke came out of the exhaust, and the exhaust is making a bubbling sound at low RPMs. I assumed an exhaust leak, but now when I accelerate hard, decellerate suddenly black/grayish smoke comes out of the exhaust sometimes. Also the idle bounces around a tad between 600-800 at idle. The only code thats being pulled is the same as always (1 bank 2 O2 sensor) which I assumed was from the off road and a failed mil eliminator. Could the bank 2 O2's be causing my car to run rich? I read on hear the rear sensors will not affect drivability. IM planning on putting the stock H pipe back on asap, but is there anything else I can check. This is driving me crazy as I just bought the car!!

The only CEL is the bamk 1 number 2 for the rear O2's, but that has always been on since the guy I bought if from put on the off road H. The smoke on first start up isnt concerning me to much (seems to happen alot) its the smoke when shifting gears (grey) and the bubbling gurgling sound that the exhaust is suddenly making. MAF? Is that Mass air filter? located behind the air filter? Excuse my ignorance but this is my first 4.6 and Im still trying to figure out where some things are.