I think that there is a speed cap, varying on each ship's top speed (I think), but if you use a turbo and a speed pad, they both add up. If someone could get a glitch where they fall out of the map endlessly, I think that may give you an answer.
Anyways, I fixed the sticky stuff by going over to the far right of the overpass on entry, and sticking to the far right all the way up to the first speed pad on the overpass. Staying in the center still has the sticky stuff though.