I cleaned out my K&N on my Dakota, and I decided to take off the air intake and then I noticed how grummy the throttle body was. So I took that off, and then I cleaned up the throttle body, and I cleaned out the upper intake as well. So I put everything all back together... and whatta difference it made. Smoother idle, much faster throttle response, and a better exhaust note.

My question is... how the heck does it get this bad? Also, how long should I wait before cleaning on the one on my F150?

 

Ditch the factory air intake and get a K&N full intake you can get to it easier with out all the plastic over it to clean it. The stock plastic holds dirt and grime under it and it builds up on the TB.

 

Yeah, that's what I am planning to do with my F150. On my Dakota, I've got the full K&N intake... it's the plastic one (the one that gains the most hp).

I just was curious on how it gets so bad...

 

Was it dirt, or filter oil?

If your getting dirt in there, you might want to check for some leaks...thats bad news.
If its filter oil, Id say your simply over-oiling the filter after you clean it.