2002 BMW 745 Please Help!1

My car is running hot, I replace tha radiadter&cap, fan clutch, resorvior it not running good its running hard sounds like a air leak when I pull the oil stick out it idle changes sounds like I hear air coming from somewhere all of my service lights stays on when I start the car it shakes fell as those it has a air leak some where I cant let it run for long time due to overheating when I start tha car and go to tha rear tha sound coming out of tha pipe its sounds really bad I was told that it misfiring.