Could a pump motor or bad flow sensor cause a small power problem and a Great Lakes hot tub to reset to 100 degress. It see when the pump is on there is a small power surge and it resets the temp. The temp when set at 100 or 91 always heats up over that temp by 1 or 2 degrees. I have tried everything under the sun and cannot figure it out

a power surge when a motor kicks on will indicate that you have a loose or weak connection somewhere, in the power. What that will, over time, cause is overheating and possible burning of connectors and/or wiring. If you can hook a multitester to the incomming spa voltage feed, check to see if your power is dropping when this happens. I'll be willing to bet it is. measure first across both L1 and L2 (if 240V) to verify this. If so, measure between each line and neutral to determine which side is causing the problem. Start as close to the spa as possible, then at each junction point all the way to your main panel in the house. When the power stops dropping out, you found the last "good" connection, and the problem is immediately after that.