Problems W/ brushless motor need help! Pleaze!

I put a 3cell lipo in my 4x4 Slash for the first time yesterday....Ran fine with stock Motor and ESC...A Friend of mine gave me a Aveox 36/24/1.5 Motor to put in it...Now I have installed this motor with the VXL ESC and when I give the truck full throttle its like the motor is "Hitting a rev-limiter" in a way...When it goes past about 60% throttle it starts doing it all the way to full throttle...I know it sounds weird but i cant think of any other way to describe the issue i am having....

I would greatly appreciate any and all suggestions...I am new to the brushless world, Ive been converted from Nitro and still learning the electric stuffs..