[BonestockNA]

Nice pictures of the ISC with deposits. Good find. This is behind a lot of rough idle/stalling with these engines. I have usually seen dry powdery deposits choking off the air bypass passage ways. Seldom see the ISC itself go bad. This is a clean up and reinstall for sure.

 

[BonestockNA]

Applying a weld bead to the tip sounds like a strange attempt to fix by a prior owner. I assumed it was some solidified carbon deposits. Why would anyone try to weld on the tip? Looks like you did a really good job reshaping it. Hope it works. Let us know how it turns out.