Did anyone else think it was kind of sudden and out of left field when Gowron became dishonorable? He was never the absolute best chancellor, what with plunging the Empire into war with Cardassia, but I always got the impression that his intentions were always good. Actually I liked the twist where we all thought he was a changeling, but that wasn't true. I also thought his dismissal of Worf was really sudden and unlike his character in TNG. Maybe Gowron was kind of a tragic character who lost his way, but it must have happened off screen.
Just jumping in with my own view on the OP:
Gowron was never dishonourable. He did a few things that were in his best interests, but he was Klingon Through and Through.
He did everything Klingon by the book up until the end.
He didn't want anything to do with Worf from the get-go until there was a chance Duras was a traitor and doing things un-Klingon while framing Worf..... but even then he still didn't want anything to do with Worf because he was dishonoured and not a part of the Empire anymore.
Skipping through, as we all know how that all unfolded and Gowron became friends with Worf, we jump to DS9.
Worf understood his invasion of Cardassia and it was simply Gowron bringing back the old Klingon ways of expansion and conquest, which was desired by many Klingons for a long time.
The other factor that was in play at this time was that Gowron also had a Changling posing as his closest advisor and General & whispering in his ear all sorts of manipulations wrapped around Klingon Tradition and thinking.....
Even during all of this, Gowron knew his Klingon Roots and they still dictated his actions, which was evident when Worf quoted Kahless to him to stop the battle between DS9 and his fleet... despite the Changelings's protests.
Bythe time the Changeling was found out, Gowron knew Klingons still needed to finish what they started and couldn't just stop.
This mentality kept going through to the bitter end.
In the last days of his life, although he was still sticking to his Klingon Roots, his personal agenda & chances of legendary songs sung of his name were being compromised by Martok's victories and thus, jealousy was setting in. This in turn made him send Martok on more risky missions to either get rid of him or at least take him out of commission and pulled back from the front lines due to injury.
What also was evident was that Gowron was starting to take on a lot more than what he could handle and it was showing in his decisions.
Despite all of this and his flaws, He took on Worf's challenge like a Klingon and he died like a Klingon... though he didn't really have a choice in the matter as Worf pretty much went at him right away. It was a good battle and Gowron fought well.
Whenever he was challenged by another Klingon regarding his rule, he never excused away from the challenge, he never blithered on about not taking the challenge.... as soon as he knew he was being challenged, he had the knife out, his eyes bulging with that odd smile and he'd fight without a second thought.
He wasn't perfect and he had many flaws, but he was never dishonourable.
While not confirmed, it certainly seemed like the writers' intention for the audience to come to the conclusion that Duras was the poisoner.
Well it simply couldn't have been anybody else.
It's the same sort of tactic the Duras Sisters pulled when they sent Assassins after Picard..... when they sent guys to Shiv Worf's brother..... when they sent guys to ambush, beat and kidnap Worf himself.
The Duras family wanted absolute power in the Empire because they could forever keep their family's dishonour a secret, or at least long enough until they changed how things run in the Empire and eventually bring about the alliance with the Romulans, whom would further ensure their House remained in absolute power as they would be their noose around the Klingon Empire.
Poisoning the Chancellor fits right into the puzzle, especially Duras's reaction compared to Gowron's when it was found out that he was poisoned.
At the same time you have one of Duras's men become a suicide bomber.
Either way, it certainly wasn't Gowron who did it.
Yes, Gowron did try to "Negotiate a deal that benefitted him and K'Ehleyr to win power" ...... one could also call it a "Bribe"...... but trying to Bribe someone is not the same as killing someone with poison like some snake.