Slight difference of opinion. The teflon coating does reduce the build up (I've cleaned enough of them prior to the teflon coating becoming common to know). The teflon coating also makes it easier to clean. Done with a bit of care you can clean it on the car to 95% to 98% as clean as you can by removing it. I have had mine off twice. The first time to clean it and found that I could do nearly as well with it on. The second time when I had to remove it to change the IIMC box and I cleaned it just because it was off.
I believe that the teflon coating was added so that Ford could quit paying for throttle body cleaning under warranty. For the most part, It did a good enough job that it would get by until it was out of warranty, but it is also my belief that the teflon coating did not eliminate the need.
When you do clean the throttle body, pay special attention to the carbon ring that forms slightly inside the bore from the throttle plate. That sems to make the biggest difference.
