I have the EXACT same problem. At first i thought it was my tires because i changed them and it seemed to go to the left instead of the right. Let me ask a question. If you brake hard does it also drift/slide to the right? What i did was what nitro dude suggested. you HAVE to make sure that the toe in (the rear) and the toe out (the front) is set correctly. Make sure the camber is set equally on all four tires. Also adjust the tweak. What is tweak? Glad you asked. Put your car on a surface that you know is flat and even. move the rear of the car until the back of the chassis is hanging over the edge (tires still need to be on the table). take a hobby knife and push the car up. both back tires should go off the ground at the same time. if they don't, take the opposite front tire and stiffen the shock. for example, if the left rear tire goes up before the right rear stiffen the shock spring on the right front tire. do this until both tires move up equally. do the same for the front. this will help out ALOT.
I went racing last night and one of the guys did all this to my car and it handled 300 zillion times better than before. plus, it went straight
...until i flipped it this afternoon. but i'm working on it now