I'm debating leaving them in because I'm sure they will be a pain to pull and they aren't leaking. My engine is absolutely disgusting so I am sending the whole thing off to a shop to be cleaned along with the head which needs a valve job. It's a 97 4.0. I can leave them as is or replace them when i get it back from the shop since I'm also replacing every other wear component. Also I KNOW what oil changes are. Apparently the previous owner didn't

 

100% they should all be pulled, especially the one that is behind the flywheel

Any other decision would be utter madness (in my humble opinion )

I drill a tiny hole then use a self-tapping screw on a slide hammer to extract them, so the lands are not harmed, then clean the lands of any corrosion

talk with shop anyway, I prefer not to bash them in though, and I prefer to attend the installation

There is a % of the population that never change their oil, coolant, brake fluid etc...ever...even if a light comes on, until it fails to proceed

 

Thanks for the response. I'll be sure to replace them