Fix It Or Get Another

My truck is starting to show it's age and I'm torn about what to do.  It's a 2011 model so it's not super old but she's no spring chicken either.  A variety of things have happened to make me question whether I should keep the truck or get another.  Back in August, I was taking my daughter to work and the truck actually overheated.  I had to pull over on the side of the road in 5 o'clock traffic and wait for the engine to cool down.  I can't run the air conditioner for fear of the vehicle overheating.  Something is wrong with the driver's side window and I can't let it down.  I need a set of tires.  I need to get the brakes done because they are starting to squeak.  I need to have the shocks and struts replaced.  I've also been told the rear control arms need work.  All in all, that seems like a lot of money to invest in an 8 year old car.  I've learned in the past that when you start putting more into the car than what it's worth, it's time to move on.  Barring any major problems, I should be able to pay it off at tax time next year.  At that point in time, I would only have to worry about maintenance and insurance.  On the flip side, I could look into getting another vehicle but that would stick me with another car payment for five or more years.  I'm still undecided which option to take.  I'm still not sure if I should fix it or get another.