I have a 2003 Ford Ranger Edge 4x2 with the 3.0 engine. (83,000 miles)

I been noticing my speedo is dancing at idle. From the video i shot while waiting for my food, it looks like the needle is dancing to the music on the radio.
The other thing i noticed is my idle seems a bit high at times, and it keeps changing everytime i come to a stop. I think it usually idles around 800rpm, not it seems to go to 1000 or 1100. I understand the number might not be accurate, i'm going by what i can visually see and from the changes i hear. (after 10 years of owning the truck, that happens)

I saw there was another post about just the dancing needle, and i cleaned my battery contacts and made sure it was tight.

 

I had the battery tested and it came up bad, got a free BOSCH battery as replacement.

It looks like that fixed the problem. I did notice the negative terminal on the old battery had a lot of excessive corrosion. I will have to keep an eye on that to make sure it doesn't happen on the new battery.