Car electrics glitching

[carlin]

Hi Guys,

Wonder if anyone can help me.

I little puzzled with my electrics in my car.

This is what I'm currently running
LRP SXX TC NEW
SP V3.0 6.5t or LRP x12 6.5t
Ko Propo Servo
Ko Propo Rec 302f - Ko esp III Handset
Lipo saddles Intellects

The problem i'm having is when the car reachs top end speed it's stuttering if you know what i mean like it's holding back.

This is what i have tried so far to cure it but still doing it.
Tried two different motors
Change Crystals
Different Servos
Diff Sensor wires

I'm little confused know, I'm sure it's something to do with the speedo but it's Brand New.

Anyone have any ideas what it could be