Intermountain FP-7 stall

[Palmland]

We have just installed a Walthers double crossover into our passenger terminal. We now find that our FP-7's hesitate and often stall on the crossover. It appears that, due to spacing of the trucks, three of the four axles are on the two insulated frogs at the same time. Shouldn't the one axle be sufficient to keep it moving?