[Tommy]

Voyager,
You seem unwilling to give up on the idea that the gauge may be the problem. To safely resolve that issue I suggest one of two approaches. For about $20 you can buy an aftermarket temp gauge at any auto parts store and temporarily install it while leaving your stock gauge in place. If it does the same thing as the original gauge, then the gauge is not the problem. Another option, if the temp spikes occur while the engine is idling, is to take it to a repair shop or someone with an infrared temp sensor and have them see if their sensor spikes at the same time your gauge does. If you want an infrared sensor of your own, there is a Harbor Freight store that sells them not far from you.

It seems to me you need to resolve your doubts about the gauge so you can move on to solving the overheating problem if there is one.