Funky Keg Smell

So i made the jump to kegging, but not all the way. I got the 3 gallon corny from midwest because i still wanted to bottle while i figured out kegging. Anyhoo i kegged my first batch with just sanitizing the keg (i probably jumped the gun on this one) The brew had some problems, taste being one of them. Fool me once shame on you... On to my second brew to keg i cleaned everything... except the lid (shame on me). The keg no longer had the fresh machined metal smell to it but the lid did. Well the whole batch tasted how that lid smelled. So i cleaned the lid by soaking it in some star san. The lid no longer has that metallic machine smell but the O ring still does. Should i get a new o ring? Also any recommendations on a good process for cleaning out a keg?

I would buy all new o-rings for the lid and for both the gas and liquid posts.

To clean our kegs we disassemble everything by removing both posts and pulling out the dip tube. We soak everything in PBW and give it all a good scrub w/ a brush. We then rinse and soak everything in star-san for 20 minutes. After that we rinse everything and reassemble the kegs.

Also make sure to clean your lines. An easy way to do this is detailed here: https://www.homebrewtalk.com/f51/diy-beer-line-cleaner-226497/

If that doesn't solve your problem then I'm of no help, that has worked like a champ for us. Cheers.