Every 3-5 min lights dim or brighten if I tune on microwave in kitchen lights in parts of house dim and microwave slows, if I tune on a fan and use the microwave the fan go faster and the lights bright please help.

Could be loose neutral(s), hots, buss or breaker connections. I would measure at the Panel, and go upstream or downstream, depending on the results.

The lights getting bright, and the fan running faster is an indication of a loose neutral.

I must suggest you do not operate these appliances until the problem is found and repaired.

I have had units such as bathroom exhaust fans burn up, smoke, etc. due to a loose neutral condition.

I will assume you have no knowledge of working on electrical wiring, and need to call in a professional.

Do this ASAP. This is not a DIY project.