Engine slows

I have 3 loops, 2 are approx 40 feet around, the 3td loop is about 25 feet.

I am running a Vision line Hudson on the outer loop, an Atlas GP 15 (TMCC) on the 2nd loop. A Lionel Legacy GP 35 on the 3td (enter loop).

Problem: The Atlas GP 15 will slow almost stop (will stop sometimes if the speed is slow) on one section of the track, it runs great on the other 2/3 of the loop.

I have taken the Atlas off on put the Lionel GP 15 on the center loop , it and the Vision line run great. It is the Atlas that slows.

I have read if I run a length of insulated wire (any gauge) between the tracks and connect the wire to a ground plug, the problem may go away. Do I understand this correct?

Brent