Just thought I would post the solution to the problem.

Culprit ended up being a coolant system that needed to be burped. Did it once on a good incline, had to add a fair amount of fluid. Did it a second time a few days later, added a bit more. Why this would cause the problem, I can only guess. But, I will take lucky over good any day.

Has not done the surge thing since then.

Thanks gents,

Mike