Mercury 200EFI Offshore Timing problem

[FireFletch67]

My 200efi offshore runs rough until 3000rpm then it runs great, I recently replaced the computer and was told that could have caused a timing problem, I am mechanically wise however, these EFI motors give me a run for my mone.

My question is how to time it, the timing is stamped on the flywheel cover I just need to know how to adjust it.............Thanks!