Is this servo junk or can it be fixed?
 

I have a Savox 1257TG for my throttle servo in my 1/8th nitro buggy. It started acting up on me today. The throttle started surging on and off so I ran out and grabbed my car. As I sat in the pit it kept surging until it was running wide open and stopped responding to any input from the tx. I killed the motor and turned it off. When I turned it on again I had no response but if I touch the servo arm it starts jumping all over. I tried switching it to another channel and it does the same, and my steering servo is fine so I know its the servo. Can anyone tell what the problem is by my description? Is it fixable, or do I have to drop another $70 on one? Is there a cheaper alternative from Savox?

It's junk. Savox is "cheaper", maybe you got a bad one or maybe set up, (end points) are not correct. If it's less than a year old, savox will fix or replace it. I have 3 of them and all work flawlessly.