Needle goes up and down when comes to stop or park

Which needle goes up and down? Do you mean the temperature needle moves when you stop or park? Is that with the engine running and up to temperature. If yes it may be normal as the reduced airflow over the radiator can cause the coolant temperature to go up until the cooling fans can pull enough air over the radiator to cool it down.
Think you could shoot a quick video of the gauge and post it so we could see the actual motion?

It's the tachometer needle. This only happens when the car has been running more than 5 minutes and when I make a stop and in park but not when I first start the engine.

Okay, the tachometer is fluctuating. Do you hear the engine also changing with the needle? How far is it changing? If you are setting still in park, does it still fluctuate when you select reverse or drive and just hold the brake? If yes, it could simply be a dirty throttle body that is trying to compensate for the dirt build up once everything has gotten warm.

No, it stops once I put it in drive and reverse only when it's in neutral and park. The RPM needle stays between o and 1,000.

And also it starts when I make a stop during intersection and stop lights. So I guess when I press my brake as well. It's not terribly that bad but I'm just bet concern since it never happened before until recently I changed the spark plugs and a new upper radiator hose.

Okay, so it's the needle moving between 0 and 1,000, does the engine seem to do the same thing, IE rev up and down or only the dash meter? If it's only the dash I would suspect a loose connection under the hood or an issue with a signal feeding back from a wire after you did that work.