2007 FORD E-350 Suspension Problems

I BOUGHT NEW A 2007 E350 HEAVY DUTY DIESEL CARGO VAN THAT DEVELOPED DANGEROUS DRIVING/HANDLING CONDITION AT APP 75,000 MILES. NEVER A ACCIDENT, ALWAYS PROPERLY SERVICED, FREEWAY DRIVING 90% OF THE TIME , LOAD EVENLY DISPERSED AND UNDER WEIGHT FOR E350. IT HAS FLOATY, DRIFTY, WANDERING HANDLING AT FREEWAY SPEEDS. CONSTANT CONDITION NOW. DEALER HAS HAD VAN 4-5 TIMES AND IN THEIR POSSESSION FOR OVER 40 DAYS OFF AND ON. 3 MONTHS PURSUING THE PROBLEM. WE HAVE REPLACED BUSHINGS, COIL SPRINGS, SHOCKS, DRIVING GEAR BOX AND ALIGNED THE VAN 3 TIMES. FORD TECH'S INVOLVED. 3 MONTHS AND $3000.00 EXPENSES INCURRED, THE PROBLEM STILL PERSISTS. I DROPPED THE VEHICLE THIS WEEK TO LET THE DEALER HAVE ONE MORE SHOT TO FIX THE PROBLEM OR REPLACE THE VEHICLE. MY SERVICE REP ADVISED ME TODAY THAT THE VAN IS DRIVING FINE AND THAT IT IS MY IMAGINATION THAT THE CONDITION STILL PERSISTS. ARGUED...

UNCONTROLLABLE STEERING WANDER. INSUFFICIENT SUSPENSION AT AND BELOW RATED CAPACITY. CONSTANT CONTINUAL CONDITION. REPLACED SHOCK ABSORBERS. REPLACED STEERING GEAR BOX. UNSATISFACTORY CONDITION REMAINS UNCHANGED.