I read a pretty good article about crankwalk a few months ago. They showed that the reason crankwalk was occurring was due to oil squirter changes in the 2G block. The squirters have a check valve in them with a ball and spring. The squirters were getting stuck at different open to closed positions and causing bearing wear. The way the shop that wrote the article fixed the problem was converting the block to the 1G oil squirters, which solved the problem. I haven't been able to find the article to see if there were any updates though.

Clint