Had a 1999 Lariat 5.4 triton with 200,000 on it and loved it, but was kind of leary pulling both horse trailers and boats with that many miles on the automatic trans.I was going to keep it for a farm truck but was still able to get a pretty good trade in on it soooo.I didn't change the spark plugs in it till 120,000 and it seemed like I got worse gas mileage with the new plugs.I have a 2007 f150 crew now with the same engine and like split said just doesn't shift the way I like it, but have no problems engine wise.As for gas mileage I have to agree with what has allready been said. Chuck