Fuel system cleaning was done at 65,000 miles since that time the vehicle "hiccups" when going 45-65 mph.Had fuel filter replaced, trans filter kit installed,cabin air filter replaced. All computer tests were completed and found okay.It appears that the "hiccups" take place when there is a light to heavy snowfall or rain. Both the mechanic and this owner are frustrated. I have taken several trips of several hundred miles and the van drove beautifully in temps between -10 and 40 degrees ??????