HAVING JUST MADE IT OVER THE MOUNTAIN PASS WITH NO PREVIOUS TROUBLE, WE STOPPED AT GAS STATION FOR MORE WIPER FLUID. WHEN STARTING UP OUR 2000 FORD EXCURSION A LOUD BOOM CAME FROM THE TRUCK. THIS STARTLED US AND OTHERS OUTSIDE OF VEHICLE INCLUDING A SHERIFF THAT HEARD IT AND CAME NEXT TO US TO SEE WHAT IS WAS. WE IMMEDIATELY TURNED OFF VEHICLE - SHERIFF AND PASSER BYS THOUGHT MAYBE EXHAUST?? WE MADE IT HOME BUT TRUCK NOW SOUNDS LIKE A LOUD PUTT PUTT TRUCK. WE SMELLED FUEL ALL THE WAY HOME. AS IT TURNS OUT #10 SPARKPLUG BLEW OUT HITTING FIREWALL. FROM TWO REPAIR SHOPS IT IS IN A VERY DIFFICULT SPOT AND IS NOT LIKELY WILL HOLD. SO, WE TOOK IT TO FORD DEALERSHIP TO SEE WHAT THEY CAN DO. WE HAVE BEEN TOLD BY FORD DEALERSHIP THAT A "BANDAGE FIX" WILL PROBABLY NOT HOLD AND OTHER PLUGS COULD ALSO BLOW OR MAY NOT - APPARENTLY THIS IS NOT NEW NEWS TO FORD OR THE OTHER REPAIR SHOPS WE SPOKE WITH. SO TO REPLACE JUST ONE SIDE OF HEAD WE ARE LOOKING AT $3680 OR $5900 + FOR NEW ENGINE. VEHICLE IS NOT WORTH THAT IN TRADE IN PER FORD DEALERSHIP - EVEN BEFORE BLOWOUT . NEEDLES TO SAY, WE COULD HAVE BEEN ON FREEWAY AND BEEN FORCED OFF ROAD (IT WAS SNOWING BADLY AND A BANG THAT LOUD COULD HAVE SPOOKED MANY.) SO THAT IS WHY I STATED THERE WAS A CRASH AS THERE COULD HAVE BEEN IF WE HAD BEEN DRIVING. ALSO, NOT SURE IF THE FUMES WERE CAUSE OF ILLNESS WE HAD THAT EVENING AND NEXT DAY. WE SMELLED FUEL AND SMOKE/EXHAUST ALL THE WAY HOME. ALSO, PLUG WAS NOT FOUND AND MAY HAVE DAMAGED O