2006 Mazda Tribute Hybrid

I WAS DRIVING APPROXIMATELY 35 MPH IN TOWN AND WITHOUT WARNING, MY ENGINE SOUNDS LIKE IT IS MAKING POPCORN. I HAD TO PULL OVER AND HAVE THE CAR TOWED TO MY MECHANIC. HE FOUND THAT THE ENGINE BLEW A SPARK PLUG. HE INSTALLED A HELICOIL REPAIR AND THEN FOUND THE ENGINE WOULD ONLY RUN ON 3 CYLINDERS. THEY THEN FOUND THAT THEY HAD TO REPLACE THE ENGINE COMPUTER AND ALL 6 IGNITION COILS OR THE COMPUTER WOULD NOT BE WARRANTED. AFTER THESE REPAIRS THERE WAS A TICKING NOISE IN THE ENGINE THAT HAD NOT BEEN THERE. THE CAR WAS THEN TOWED TO A MAZDA DEALERSHIP AS MY USUAL MECHANIC DOES NOT HAVE THE SPECIALIZED TOOLS FOR ENGINEER REPAIR, AND THEY DIAGNOSED THE PROBLEM AS METAL SLIVERS IN THE ENGINE AND RAN ENGINE CLEANER THROUGH THE ENGINE TWICE. THE NOISE IMPROVED, BUT IS STILL THERE. THE DEALERSHIP ADVISED ME THAT I NEEDED A NEW ENGINE AND THE CAR ONLY HAS 94,055 MILES ON IT. THE DEALERSHIP CANNOT EXPLAIN WHY THE ENGINE BLEW A SPARK PLUG AND AFTER INVESTIGATION I FIND THAT THIS IS HAPPENING ON OTHER TRIBUTES THAT SHARE THE SAME ENGINE WITH FORD EXPLORERS. THIS SEEMS UNACCEPTABLE THAT AN ENGINE OF THIS AGE WOULD NEED REPLACED. THE CAR WAS WELL MAINTAINED AND HAS HAD ALL THE SERVICE CALLS REQUIRED. *JB