2005 Lincoln Navigator

ENGINE STARTS TO KNOCK AN SHAKE VERY LOUDLY WHILE COMING TO A COMPLETE STOP FROM SIMPLY DRIVING 45MPH OR IT COMPLETELY LLOSES ALL POWER AS I'M DRIVING AN A LOUD POPPIG EXPLOSIONS COMING FROM THE EXHUAST AN THEY ARE LOUD ENOUGH WERE PEOPLE HEHHAVE PULLED UP NEXT TO ME TO LET ME KNOW AN AFRAID THE CAR MAY BLOW UP. AIR SUSPENSION DOSE NOT COME ON WHEN IT'S COLD AN DRIVES VERY POORLY AN MISLEADING TO OTHER DRIVERS AN LAW ENFORCEMENT SINCE I'VE BEEN PULLED OVER FOR POSSIBLE DUI BECAUSE THE CAR IS ALL OVER THE PLACE AN JUMPY. THE RADIO CUTS IN AN OUT AS I DRIVE, THE CRUISE CONTROL DOESN'T WORK. I'VE TAKEN IT TO 3 DIFFERENT MECHANICS THEY ALL SAY THE SAME THING TAKE IT TO THE DEALER BECAUSE THEY CAN'T SEEM TO FIGURE IT OUT. SO I TOOK IT TO GALPIN LINCOLN IN VAN NUYS, CA ON ROSCOE BLVD AN SEPULVEDA AN THEY JUST FOUND ONE FUEL INJECTOR NEEDING REPLACED AN WANTED ME TO $2,500 FOR LABOR ALONE TO COMPLETELY OPEN UP MY ENGINE AN SEE IF IT COULD POSSIBLY BE THE TIMING CHAIN AN REALINE THE CAMSHAFTS BUT THEY ARE NOT CERTAIN THAT'S ACTUALLY THE PROBLEM WITH MY NAVIGATOR BECAUSE THEY CAN COMPLETELY DO ALL THAT AN COME UP TO BE FINE AN BE SOMETHING ELSE BUT UNLESS I PAY $2,500 FOR LABOR TO JUST SEE IF IT IS AN HAVE THE CHANCE IT COULD NOT BE I STILL LOSE THOSE $2,500 BECAUSE IT'S A NON REFUNDABLE. WHERE AM I GOING TO COME UP WITH THAT KIND OF MONEY NOT ALONE WHY AM I HAVING TO PAY THAT FIRST TO SEE IF IT'S A MAYBE THE REASON OF ALL MY CAR PROBLEMS. HONESTLY THAT IS RIDICULOUS AN NOT GOING TO PAY THAT KIND OF MONEY ON A MAYBE ANSWER NOT A 100 PERCENT WE ARE SURE THAT'S THE PROBLEM. SOMETHING NEEDS TO GIVE AN HEAVEN FORBID MY CAR DOES BLOW UP WITH MY SON'S IN THE CAR DRIVING IT JUST BECAUSE I NEEDED TO PAY THAT AMOUNT ON A MAYBE ANSWER IS UN CALLED FOR.