i had a 2.5 in my jato then i took a 3.3 out of my friends t-maxx that he sold to me which was tuned good but when i put it in my jato it now cuts out when it brakes so i tried tuning it to my past 2.5 settings and it still cuts out under braking whats wrong?

Your throttle is closing when you apply the breaks. You need to turn the throttle stop screw so it dose not close when you hit breaks.

whats the throttle stop screw

Sorry there is not throttle stop screw on the jato. It is the idel screw. It will be next to the HSN if you look from the back of the truck. I think you want to turn it in.

That is what the idle screw is...It stops the throttle from closing all the way. Thus the term 'throttle stop screw'.
You should read the manual, or watch the DVD, to learn some of the more important aspects of running and tuning a nitro engine.

I had the same problem yesterday with my 3.3. Turn your idle screw clockwise...