2001 Dodge Neon

Hello. I really need some help with my 2001 Dodge Neon SE. I am a college student, and already have spent more than a couple grand for the car than expected. To top off the list, I did a calculation, and was able to determine that I am getting roughly 13 miles to the gallon, which is worse because my college is pretty far, and I don't have the money to refuel every other day. Anyway, I did the engine diagnostic codes and my hair stood straight up. I had the following codes, which I looked up:

p1684 - Driver 5, Line 4
p0743 - TCC Enable Solenoid Circuit Electrical
p0202 - Injector 2 Circuit Control
p0201 - Injector 1 Circuit Control
p0302 - Cylinder 2 misfire
p0508 - Idle Air Control Circuit Low

I also want to mention that while my car is idle, it jerks in random beats constantly. Other times, while driving, I hear a loud pop come from the engine.

Any idea how much it would cost to fix some of these or how would I be able to do it myself, especially the gas comsumption problem? I would need it done as cheap as possible, because I'm already in a financial burden with paying for classes and books. Thank you all very much.
August 30, 2007.

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