It sounds more like a reciever problem and the first casulity was the steering servo. No, if the reciever is working properly the steering servo and throttle servo would not effect each other, at least not to the best of my knowledge.
Couple of questions...
What car is is?
What kind of radio? 2.4 system? FM or AM with crystals?
What kind of battery are you using and how many volts does it put out?