I java a savage x with the 4.6 and factory servos and a traxxas tx/rx and every time I set the tx to 50/50 the engine runs wide open and the throttle has no control what is my problem

Set your transmitter at 70/30.

That's what it's set to now I'm just wondering why it only does it on 5050

50/50 is for electric. 70/30 is for nitro. When you move it to 50/50 it moves the neutral point in the radio and thus moving your throttle servo as well. leave it on 70/30 and you will be fine.