You could get a 97-08 F-150 4.2. You would get a low mileage engine for a reasonable price. A tune and 01-04 fly wheel would be needed. You would also have to cut the main bolts (cover with a bag) or get a 01-04 oil pan. You would gain some serious tq and save some money. Ebay 3.8s are $1650 and engine shops cost more (about$2200)+ all the little stuff like new radiator fluid, oil, ect.
new engine,1.7 rocker arms,Pipes exhaust, shorty cats , shorty headers,under drive and overdrive pulleys,4.2 upper plenum, throttle body spacer, cold air intake, stage one clutch, shorty shifter, and tune. 8.8 in storage