To put it simple it's uneven weight on the differnt corners of the car. So you might have too much weight on the right rear compred to left rear. This could be caused by a twisted chassis or weight distribution, uneven shock lenght or spring lenght and the list goes on and on. It's very important for the cars setup to work right.

easy way to fix it without buying expensive gear. Get a level table of setup board. draw a centre line and nail some nailed into it so you can place your car on it without the wheels touching. draw a center line on the chassis. then sit the car on it race ready without body. the car should not fall from one side or the other, if it does add weight to the oppisite side.

then take off all you shock and check the lenght and spings and fix. check you droop setting if you have them muct be equal. then put them back on. Take the mails out and place the car lined up with center line of the chassis and the setup board. Set your right height and make sure your peload collars are even from sie to side.

The car should be right but do this next. with the car in the center lift the car up with a knife via the center of the rear or front and see if both wheels come off the board at the same time. If not then if your doing the rear the the left side comes up first adjust the RIGHT FRONT of the car with more preload or the left front with less preload. this should balance it out. the do the front and adjust it on the rear.

Should be a lot better to drive after all that. If you have heaps of difference in the shock preloads then I bet ya your chassis is out of square or tweaked.

If you have a problem understanding this just reply again.
Coxy.