Can drive motor affect steering servo?

[sparkycuda]

I had my PH350 off-road dump truck driving around the basement for the first time last night. But, whenever the truck is above about 1/3 throttle, the steering servo gets a mind of its own and goes to the left. Sometimes it cycles from center to left and back. Whenever the drive motor is off or at very low speed, steering works perfectly. I have an 85T crawler motor and using Taser 15 ESC. Steering is Hitec HG-645MG servo. Radio is Spektrum DX6i. I mounted the servo parallel to and about 1/4" from the motor body - a very clean setup - but is the EMF from the motor causing the problem with the servo? I'm new to the R/C stuff, so I may have made a basic boo-boo.

Any help would be greatly appreciated. Thanks!

Ken