Whats wrong with my car? Will it make a 500mi trip? (Az to ca)

List:
-I can't turn on the overdrive, when I do, the RPM's go up and down like crazy. From 2000-5000.
-If I turn the OD off its fine.
-Sometimes its really slow to accelerating. But, once I press the gas to a certain point, it like jumps and then accelerates really fast.
-I smell gas all the time.
-When I turn it on in the middle of the day, sometimes it doesnt start. I'm in az so its like 110 degrees out. It turns on, but it vibrates, makes a knocking noise, and shuts off. I have to turn it on and off 5-15 times to get it started without it shutting off or vibrating. Only does it when its hot, or has been running for a while.
-Just recently, when I fill my gas tank, it backs up. No matter what I do, a little gas will come out and then go back in.
-The radiator hose has a small leak, so does my oil. But, I check that every week and its fine. Along with my transmission fluid.

Would it make a 500mi trip? If not, what should I get fixed so it makes it? If I were to get a diagnosis, would everything thats going on show up?