If you have replaced everything- Servo (For steering), receiver, speed control and motor, and you still have problems, then maybe there is a problem with your transmitter. If you let your transmitter sit for 2 years with batteries in it, they may have leaked acid and caused some damage.

Have you tried changing all of the items at once? In other words, have you tried to run it with the new motor, new ESC, new receiver and new steering servo all at the same time?