2002 FORD E-350 Unknown Or Other Problems

THIS 350 ECONOLINE, 8CYL., EXTENDED BODY VAN WAS PURCHASED NEW, AND I AM THE ORIGINAL OWNER. THE VEHICLE HAS ONLY 120K MILES ON IT SINCE 2002. BEGINNING SEVERAL YEARS AGO, MY MECHANIC COMPLAINED OF SEVERE FRAME EROSION, HAVING HAD TO REINFORCE AND RE-WELD SEVERAL PARTS BACK ONTO THE FRAME, INCLUDING BUT NOT LIMITED TO THE BRACKETS WHICH SUPPORT THE REAR LEAF SPRINGS. (TWO OCURRANCES-- LEFT AND RIGHT SIDES). LAST WEEK, MY EMPLOYEE COMPLAINED OF SOME REAR END SWAYING AT MODERATE SPEED CORNERING. WE DISCOVERED A CROSS-TIE CONNECTION BETWEEN THE SIDE RAILS AT THE REAR OF THE VEHICLE'S FRAME HAD ROTTED AWAY, THUS CAUSING SOME UNWANTED FRAME MOVEMENT. IF IT WEREN'T FOR A HEAVY-DUTY TOWING PACKAGE I HAD PURCHASED WITH THE VEHICLE IN 2002, I BELIEVE THE LEFT AND RIGHT SIDES OF THE VEHICLE'S UNDER-FRAMING WOULD HAVE TWISTED AND SEPARATED FROM THE BODY YEARS AGO ! ALSO BEGINNING A FEW YEARS...

BLOWING OUT SPARK PLUGES.