Buying F series information. Need comments.

Ok so I am in the market for a new truck, I feel my ranger is too small for me and I would definately not want to get hit in that micro truck anyways so I am looking to sell it and buy a f series but I want a 250 or above. I want to be able to pull a horse trailer or a car trailer so I need a truck thats willing to work. Also my budget it about $4000.00 and autotrader has some canidates but I need all of you truck pros to tell me what to look for wrong with these trucks. like mechanical failures that sometimes happen alot to a certain year or something I really dont want anything older than 90. Please help me find out what to look for and what to watch out for. Thank you. oh and I believe I want a fuel injected one not carbeurated. and I am seeing alot of 460ci engines any good??