Temperature is guage on dashboard is jumpy. For example, it jumps from 200 to 140. It also moved as high as 250.

I'm having my engine coolant flushed today to keep the temp around 200 like before.
Do I need to replace temp sensor and thermostat too?

Thanks.

Jumpy as in INSTANT changes in temp? If not, over how long of a period of time? You need to get alot more specific.

(FYI, coolant doesn't 'cool'. Water cools. Antifreeze just keeps it from freezing for awhile, the point is that it'* not generally the condition of the fluid that causes issues like this).

Whether it'* the ECT or the Stat will depend on how you more accurately describe the problem.

Are you low on coolant at all?

sounds like possibly low on coolant or an air bubble in the system.

Flushed engine coolant and replaced temp sensor. Now, temp. settles at 218-228 after driving for more than 5 min. This is acceptable to me. What still bothers is the temp. guage still jumps instantly all over with small pauses (e.g. 100 to 180 to 140 to 270 to 200). Crazy. This happens when starting from cold engine. So I know the guage is wrong when it jumps to 270 within few min. of starting a cold engine.

What should I do/check next?
Thanks.