It could be the intermediate levers and associated repairs. Were the shafts replaced also?

On the CCV, did you check if you have any of the "cheese"?


Apparently, replacement of not just the intermediate levers should be done. The shafts should have been replaced too.
http://www.xoutpost.com/676246-post9.html
http://www.xoutpost.com/821607-post13.html

After several lever/shaft replacements, cylinder heads may have to be replaced.
http://www.xoutpost.com/715524-post4.html