I put 8 brand new BOSCH injectors. Started 1st by the ones on passenger side. Drove the truck like that, the ticking was still there but at a really low level.
Next week, put the 4 driver side injectors...., and ticking comes back

:WTF:
This will stay as is once I get time enough to fight with the roller lifters :mad2:... or may be I'll try flushing the oil circuit, once I find which flushing fluid to use