Can you move the problem loads to the other leg of power?
It sure sounds like you're on the same phase.
Trading breakers... that is moving your circuit load from A phase to B phase might be all that you need.
As ever, double check your neutral and ground bond. You want that sweet.
Also look out for bad make-up and or corrosion, especially along any path to motor type loads. Until back-EMF kicks in they can pull the voltage down. Poor connections in such a situation operate as a choke and cause the pull-in period to lengthen. The extra PxT shows up as hot spots along the path.
All of the above is cheap to check out and is far more likely to solve the problem.
