Current lithium level is 1.66, can this cause symptoms like, exhaustion, sleepiness, off balance, weird visual disturbances, shakiness,jerky muscles?

Yes!: The symptoms you describe can all be due to a high lithium level. It's very important to keep the level within the therapeutic range, and levels over 1.5 are considered toxic. However the timing of the lab test relative to your dose matters. Please contact your physician as soon as possible for instructions on what to do with the dose and when to check again.