if Itachi is stronger then why didnt he take Naruto?
or even hurt Jiyaira at all

and no Orochimaru said he feared him not anything about being stronger, reread that chapter

if Itachi was truthfully stronger then Jiyaira he had Jiyaira outnumbered two to one, Kisame and Itachi both were able to fight but they opted to run.

Even IF Itachi was too 'tired' to fight Jiyaira it still doesnt explain why Kisame and Itachi didnt fight him at the same time if we're yet to see all of Itachis powers.
If we're truely yet to see all his powers then why wouldnt he have accomplished what he set out to do, instead of failing.

even if Orochimaru and Jiyaira are even when fighting each other it doesnt mean that other people will be able to defeat both of their styles by simply being stronger then one of them.
think of it as when Tenten fought Temari, it was the worst match possible for her as Temari could deflect her only attack, while if Tenten was matched up against someone else who couldnt shes strong as she never misses unless forced to.
its the same principle - Orochimaru uses seal based jutsu which Itachi can copy which means Orochimarus main weapon is useless while fighting Itachi. It doesnt mean that Itachi can beat everyone on Orochimarus level though, it just means that Orochimarus main attacks cant work against Itachi.

That means that other people of Orochimarus level that dont rely on seal based jutsu will do far better against Itachi. such as Tsunade