Best used truck for a college student?

I currently drive a 2003 Ford Sport Trac Adrenalin. The truck itself is gorgeous, I have maintained her well and treat her well. However, it's powertrain does not return the favor. I religiously maintain all fluids and keep up on maintenance yet it still seems to break down. I bought this vehicle with 52K miles for $7900 and have put about $4000 into it in repairs in less than an year. It averages around 16-17 MPGs on the highway and 11-13 in the city. Due to my location, I drive around 300 miles a week going back and forth to the university, work, and back home. I also work construction on the weekends so I occasionally need to haul a trailer or weight under 1000 pounds, which my truck can barely handle. I need something under 12K that is extremely reliable and will get me through three more years of college without having to lift the truck every weekend. Payments over $300 a month would be stretching it. Something that doesn't get F-450 like gas mileage would be nice.

Hi so now age and hard work has taken it's toll so as this is personal finance that is for you to work out.