I put a new thermostat in my 2001 tonight and I noticed the throttle body had quite a bit of gunk in it so I thought id pull it off and clean it while I had things apart. Here are some before and after pictures: I can't believe how filthy this thing was! After cleaning it, I can already tell throttle response is better. Seat of the pants feel is also better!

 

Yuck.
I would take the entire intake off and clean it out, I am sure the passages are nasty if that is how the throttle plate looked.
Also probably time to replace the PCV.

 

^^^ Agreed.... looks like a bad PCV valve

 

I did clean the intake with it on the truck, and I could tell right after that the throttle response was faster after cleaning it. Whorls a bad pcv throw a cel?

 

It won't always throw a code until it effects another component.
I had the hose "blow out" in the elbow on mine. It acted as though the TPS was going bad for a couple days before it threw a code. I replaced the TPS, cleaned the small bit of varnish inside (nothing like yours) and cleared the codes.

It ran fine for about 2 hours and threw a code again. Turns out the O2 sensors had been effected and had to replace all 4 of them.

Then again I've had all sorts of issues with this truck. The passenger side manifold gasket was leaking so that could have also contributed to the demise of the sensors as well as the bad PVC hose.

 

I gotcha, I'll check it out once!

 

I didn't know PCV can cause that much damage. Thanks for sharing. I will check mine, too.