i replaced the filter on my 02 ranger air filter with a new k&n filter and when i opened up the old filter the box was filled with acorns.
im sorry is this common for people?

 

No, I would say a squirrel/chipmunk was using it for a stash house
Check the larger hose from rad support to air box, also the pre-warmer tube that pulls air from around exhaust manifold on cold start, these are often removed or broken