RE: RTR3 having hard time going striaght!!!!
Also check servo saver. If it has to much slop in it replace the clips or the whole thing. Also make sure you have the correct servo horn/adapter for your servo. Each brand of servo has it's own specific size and number of splines on the output shaft, so if your using say...hitec servo and the horn/servo saver is for futaba, it will not sit correctly and under stresses of driving will cause the horn/saver to slip on output shaft causing the symptoms you describe.