Feels like someones fishtailing me!

For the past few months i've come notice that when im driving, usually at higher speeds on the highway, when i let off the accelerator then push back down to get some more speed. It feels like someones trying to fishtail me, the whole rear end shifts over. Now i was told and i am aware that all my rubber bushings/linkages need to be replaced in the rear, along with the shocks and struts. but before i tackle that huge expence on my own, i'd like to know if there is anything in particular i should look for, or anything that i failed to mention above.
Thanks in advance