Hello all,
I have a 1997 F-150 4.6. I have a cel and a heavy pinging that seems to get better the colder the outside temp is. If I unhook battery , the rehook the cel is gone for a day or so and the pinging is much less, but in a day or so it comes back on and condition worsens. Any thoughts? Thank you.

 

If you get the code read it will tell you what system is involved.
Clearing the code is not a repair.
My bet from your description is it's EGR related.
Good luck.