I couldn't think of a single bad episode, so I was curious what other people thought was the worst. Both the pilot and the second Queen of Jordan were rated the worst, at 7.2. Still a pretty good rating!
Note that the Y axis on each chart does not go from 0-10. They are all 7-9.5.
Data source: IMDb
Tools used: LibreOffice Calc, GIMP
Season 1 chart Season 2 chart Season 3 chart Season 4 chart Season 5 chart Season 6 chart Season 7 chart Raw data
Season
Episode
Chronological
Name
Rating
1
1
1
Pilot
7.2
1
2
2
The Aftermath
7.5
1
3
3
Blind Date
7.8
1
4
4
Jack the Writer
7.4
1
5
5
Jack-Tor
8.0
1
6
6
Jack Meets Dennis
7.6
1
7
7
Tracy Does Conan
8.2
1
8
8
The Break-Up
7.7
1
9
9
The Baby Show
7.9
1
10
10
The Rural Juror
7.9
1
11
11
The Head and the Hair
8.1
1
12
12
Black Tie
8.4
1
13
13
Up All Night
7.9
1
14
14
The C Word
7.8
1
15
15
Hard Ball
8.3
1
16
16
The Source Awards
7.7
1
17
17
The Fighting Irish
7.8
1
18
18
Fireworks
8.1
1
19
19
Corporate Crush
7.7
1
20
20
Cleveland
8.0
1
21
21
Hiatus
8.1
2
1
22
Seinfeldvision
8.2
2
2
23
Jack Gets in the Game
7.9
2
3
24
The Collection
7.7
2
4
25
Rosemary’s Baby
8.1
2
5
26
Greenzo
8.2
2
6
27
Somebody to Love
8.1
2
7
28
Cougars
8.0
2
8
29
Secrets and Lies
7.7
2
9
30
Ludachristmas
8.1
2
10
31
Episode 210
7.9
2
11
32
MILF Island
8.3
2
12
33
Subway Hero
7.6
2
13
34
Succession
8.3
2
14
35
Sandwich Day
8.0
2
15
36
Cooter
8.3
3
1
37
Do-Over
8.1
3
2
38
Believe in the Stars
8.4
3
3
39
The One with the Cast of ‘Night Court’
7.9
3
4
40
Gavin Volure
8.1
3
5
41
Reunion
8.5
3
6
42
Christmas Special
7.7
3
7
43
Señor Macho Solo
8.0
3
8
44
Flu Shot
7.7
3
9
45
Retreat to Move Forward
7.9
3
10
46
Generalissimo
8.5
3
11
47
St. Valentine’s Day
8.2
3
12
48
Larry King
8.0
3
13
49
Goodbye, My Friend
8.0
3
14
50
The Funcooker
8.2
3
15
51
The Bubble
8.1
3
16
52
Apollo, Apollo
8.4
3
17
53
Cutbacks
7.6
3
18
54
Jackie Jormp-Jomp
7.9
3
19
55
The Ones
7.9
3
20
56
The Natural Order
7.8
3
21
57
Mamma Mia
8.0
3
22
58
Kidney Now!
8.6
4
1
59
Season 4
7.7
4
2
60
Into the Crevasse
7.7
4
3
61
Stone Mountain
7.7
4
4
62
Audition Day
7.9
4
5
63
The Problem Solvers
7.9
4
6
64
Sun Tea
7.7
4
7
65
Dealbreakers Talk Show #0001
8.1
4
8
66
Secret Santa
8.0
4
9
67
Klaus and Greta
8.3
4
10
68
Black Light Attack!
7.9
4
11
69
Winter Madness
7.4
4
12
70
Verna
7.6
4
13
71
Anna Howard Shaw Day
8.5
4
14
72
Future Husband
7.7
4
15
73
Don Geiss, America, and Hope
7.9
4
16
74
Floyd
7.8
4
17
75
Lee Marvin vs. Derek Jeter
7.8
4
18
76
Khonani
7.4
4
19
77
Argus
7.6
4
20
78
The Moms
7.7
4
21
79
Emmanuelle Goes to Dinosaur Land
8.1
4
22
80
I Do Do
8.5
5
1
81
The Fabian Strategy
7.9
5
2
82
When It Rains, It Pours
8.2
5
3
83
Let’s Stay Together
7.7
5
4
84
Live Show
8.5
5
5
85
Reaganing
8.0
5
6
86
Gentleman’s Intermission
7.8
5
7
87
Brooklyn Without Limits
7.9
5
8
88
College
7.8
5
9
89
Chain Reaction of Mental Anguish
7.6
5
10
90
Christmas Attack Zone
7.9
5
11
91
Mrs. Donaghy
8.2
5
12
92
Operation Righteous Cowboy Lightning
8.3
5
13
93
¡Qué Sorpresa!
7.9
5
14
94
Double-Edged Sword
8.3
5
15
95
It’s Never Too Late for Now
8.2
5
16
96
TGS Hates Women
8.2
5
17
97
Queen of Jordan
7.5
5
18
98
Plan B
7.8
5
19
99
I Heart Connecticut
7.6
5
20
100
100: Part 1
8.0
5
21
101
100: Part 2
8.4
5
22
102
Everything Sunny All the Time Always
7.9
5
23
103
Respawn
7.6
6
1
104
Dance Like Nobody’s Watching
7.9
6
2
105
Idiots Are People Two!
7.8
6
3
106
Idiots Are People Three!
7.9
6
4
107
The Ballad of Kenneth Parcell
7.7
6
5
108
Today You Are a Man
7.8
6
6
109
Hey, Baby, What’s Wrong?: Part 1
7.7
6
7
110
Hey, Baby, What’s Wrong?: Part 2
7.9
6
8
111
The Tuxedo Begins
8.4
6
9
112
Leap Day
8.1
6
10
113
Alexis Goodlooking and the Case of the Missing Whisky
7.6
6
11
114
Standards and Practices
7.9
6
12
115
St. Patrick’s Day
7.6
6
13
116
Grandmentor
7.4
6
14
117
Kidnapped by Danger
8.2
6
15
118
The Shower Principle
7.4
6
16
119
Nothing Left to Lose
7.5
6
17
120
Meet the Woggels!
7.5
6
18
121
Murphy Brown Lied to Us
7.7
6
19
122
Live from Studio 6H
8.5
6
20
123
Queen of Jordan 2: The Mystery of the Phantom Pooper
I'm surprised the end is so high. I've seen the first 3 or 4 seasons a bunch of times because I'd rewatch them as background noise between seasons, but I remember really not liking the final season. I can't remember any specifics because it's been so long, but I haven't gone back and watched it again since it came out because it was so disappointing. I do remember not liking Liz's boyfriend at all, and for some reason I hated the final episode.
I've been watching the show with my partner recently, but we're only half a dozen episodes in because it's just filler for when we're not in the mood for an episode of something heavier.