There are probably too many to list from notable women, but they have to be in big races to be called the "worst" so I won't give any of those.
FWIW, I don't think Salazar choked at the Olympics. I was a huge fan back then and while we didn't have the internet, magazines actually did a good job with interviews and I read everything you could back then. Something to keep in mind: this was the best field probably ever assembled for any Olympics, the beginning of open professionalism probably contributed to this, but consider who was in the field:
1 Carlos Lopes (POR) 2'09:21
2 John Treacy (IRL) 2'09:56
3 Charlie Spedding (GBR) 2'09:58
4 Takeshi So (JPN) 2'10:55
5 Robert de Castella (AUS) 2'11:09
6 Juma Ikangaa (TAN) 2'11:10
7 Joseph Nzau (KEN) 2'11:28
8 Djama Robleh (DJI) 2'11:39
9 Jerry Kiernan (IRL) 2'12:20
10 Rod Dixon (NZL) 2'12:57
11 Pete Pfitzinger (USA) 2'13:53
12 Hugh Jones (GBR) 2'13:57
13 Jorge González (PUR) 2'14:00
14 Toshihiko Seko (JPN) 2'14:13
15 Alberto Salazar (USA) 2'14:19
16 Mehmet Terzi (TUR) 2'14:20
17 Shigeru So (JPN) 2'14:38
18 Ralf Salzmann (FRG) 2'15:29
19 Henrik Jørgensen (DEN) 2'15:55
20 Ahmed Salah (DJI) 2'15:59
21 Agapius Masong (TAN) 2'16:25
22 Gidamis Shahanga (TAN) 2'16:27
23 Eloi Schleder (BRA) 2'16:35
24 Karel Lismont (BEL) 2'17:07
25 Allan Zachariassen (DEN) 2'17:10
Lopes was clearly the best 10k runner in the world over the previous 10 years based on time. Only Rono or Mamede really came close in terms of times. 3X WCCC winner. First man under 2:08. In hindsight, Lopes was clearly the best in that field. Only Deek, Salazar or Seko at their best could have beaten him. Dixon was too big.
Deek was the World and Commonwealth Champ and the WR holder at 2:08:18, but no matter what else he had going for him he could not cruise 25 laps at 27:20 like Lopes could.
Treacy was 2X WCCC champ and a 27:49 guy and had been in 2 Olympics in the 10k.
The Soh brothers (4th and 17th) were solid 2:09-2:10 guys every year, twice a year.
Ikangaa was hugely talented and eventually ran 2:08.
The Djiboutians (8th and 20th and another guy in about 30th) were huge talents and I can't remember where they had their breakthrough before the Games.
Dixon had been a world-class runner for 12 years or so by then and was right near the best in the world at 1500 or 5000m for all of the 70's. He also dominated road racing in the U.S. in 1980 (because of the Moscow boycott) and had that 2:08:59 win at NYC.
Seko was an assassin, who had won Boston once and Fukuoka FOUR TIMES by 1984. he also had run 27:46 for 10k and had run 1:49 for the 800m when he was just 19 or so.
Deek was the favorite (since he had seemingly won marathons in every way that you could -- and he had won the Rotterdam showdown with Lopes, Salazar and some others), but the theory was that he coudl not run away from Dixon or Seko and one of them would outkick him.
Salazar, on the other hand, had dominated everything he did for a while: indoor 5ks, road 10ks, marathons (undefeated), American records at 5k/10k, winning the WCCC trials and placing high at the WCCC ... until Rotterdam 1983.
He was beaten back to fifth I think, and really this is where he started to decline. He was last at the '83 WC 10k and then took 5th at Fukuoka, so he had been beaten by DeCastella, Lopes and Seko by this point. he also struggled with his health during this time saying that although he won the '83 Nat Champs at 10k it was very hard to do so. He ran around fifth I think at the Mt SAC race that had Porter, Cummings, Salazar and a few others right around 27:45. Then, of course, he lost the Marathon OT to Pfitz in his slowest time ever.
Some people say that he just wasn't as good as we made him out to be over 1980-1983, but I think he was just not as good as those years and it took a while to show this.
The '84 Olympic marathon was dominated by great XC runners and 10k'ers and Salazar was both of those. At his best I think he would have run with Lopes to the end and lost, but I just don't think that he was at his best by then. However, I don't think he choked.