when i leave a parking lot and like try to get in to fast moving traffic i hit the gas and my back end smacks hard even on little bumps. and when im driving down the street the same thing happens. can someone help me. i think it is either the struts or coil springs but cant afford to do both if its not one or the other.

 

Sounds like it's time for new shocks, the back ones are cheap and easy to replace.