I have a gen 3 5.3 and i recently had the heads resurface due to a head gasket and we also replaced the lifters. Now i can hear like a knocking im not sure what it is but sounds like the driver side i remove the plugs and #3 add oil all over the threads and electroid could this be a bent valve or maybe push rod rockers seem find

 

 

Oil on the is either a stuck oil ring on the piston or a valve stem seal.. be willing to bet if it was not oil fouled before its a torn valve stem seal

 

What will be the ticking

 

Lifter or maybe a loose rocker.... could even be something with the valve spring... just recently had to deal with that on my yukon....

 

I also agree with madmann about a compression test and maybe a vacuum guage to see what is truly going on