I second the Flysky GT3C, it's agreat budget radio, I have two of them.
Did you do a complete rebind and calibration? It will show how to perform that if you don't know in your user manual.
Welcome in @bleckan , what's the reasoning for four channels if you don't mind me asking?
Throttle and steering is all you need in a buggy.
Also you mentioned you are trying to get it to run better, what is it that you don't like?
Or did I just misread your post?