She's still got her noble moments, such as the time hank got suspended from the shop teacher substitute position and she decided to run for the "Substitute Teacher Of The Year" award on his behalf as "mrs. Hank Hill", but even then there were clear ulterior motives (shown by her speech in the end)
She's still a great character in the situations where she doesn't let her ego get in the way, but she could really benefit from having some humility and admitting she's sometimes wrong.
She gets REALLY self centered from season 8 onwards. Even the writers said they regretted doubling down on the trait in the later seasons. I still love Peggy and Peggy episodes, and she still has her moments (season 11’s drag queen episode) but it’s pretty heavy in the later episodes.