Tires too small would increase your acceleration. OEM tires are
Consider a tune up, including spark plugs, wires, air filter, fuel
filter, and a fuel additive like techron. Then check out the
acceleration again. Disconnecting and reconnecting the battery, to
clear the computer, may help too.
54K MIGHT also mean it's time to:
change the transmission, differentials and transfer case oils
check the brake pads before they eat the rotors for lunch, they might
check the belt and hoses for cracks
coolant flush and replacement
top off the brake and power steering fluids.
check the spare for air