Elviscaretaker
Gold Member
Chicago is East for me
So, East on I-90.
Try towing with the tractor at different positions on the trailer. Too much tongue weight and you can get a "porpoising" action, which is what it sounds like you are getting. Too little tongue weight and you get fishtailing.
Also, how high is your hitch? You want to make sure the trailer is level to slightly lower in front than in back. It the trailer sets too high in front, it's hard to get proper tongue weight.
Is the run away brake actuator working properly? That is, are you sure it's not engaging, say on and off, as you go down the road?