RE: new owner of a volcano pro
try testing the throttle responce with the servo unplugged from the reciever.
and i assume you re-calibrated the esc to your new spektrum radio?
I have had a servo go bad before, and it effected throttle...made it glitchy.
If the truck isnt that old, then redcat should replace the ESC for you.
Or you can find the ezrun 35amp esc for around $40 new.
Better yet, upgrade to a ezrun 60amp...or even a traxxas vxl ESC if you can spare the cash.
on the battery, the # 3500 or 5000 refers to the capacity of the battery...not the voltage. so a 5000mah pack will get you longer runtimes then a 3500mah.
so you can run anything you want, a 2000mah or a 6000mah(yes the make them that high.) it makes no difference to the ESC.
also, the ESC can handle a 8.4v 7 cell nimh pack...which will get you performance similar to using a 2s lipo pack.