working on speed

^^^^^This (probably)

Get your running up to 40mpw consistently, mostly easy.  (sometimes hard, but MOSTLY easy).  

The guy that passed you...  he runs 50mpw.

More endurance can be used to run the same pace for a longer duration or to run the same duration at a faster pace. 

x2.  Especially considering that I never said to run more, just that endurance was the limiter, not speed.  I asked 2 questions to get more information to provide informed advice rather than making assumptions.

I doubt it....very few people run 200 miles per month.  He may just have more years running....or maybe he's just talented.  My 14 year old ran a 17:20 5K off the bike this year in a sprint....he never ran more than 20 miles in a week.  There are lots of reasons that people can run faster than other people.....but I would agree, based only on what the OP posted so far, that the OP needs some long, slow, endurance work.  If "your lungs can't handle it" then you are setting yourself up for injury to do alot of speed work now IMO.

A 400 and 10mi are two pretty different beasts.  A 5k and a 10mi, not so much.  The OP lacks endurance and does not need to run a lot of sub-7 min pace in training to reach his goals.  There is no "speed" endurance different from "long distance" endurance.

As others have pointed out, a 400 and sprint tri are very different.  Maybe this chart will help:

A 400 takes approximately 1 minute.  Efforts for such a short period of time utilize anaerobic energy pathways (Adenosine Triphosphate, Phosphocreatine, and Anaerobic Glycolysis).  Energy for anything longer than about 4 minutes is provided almost entirely by aerobic pathways.  So, whether it's a 5K, sprint tri, marathon, or ironman, the primary limiter of performance in healthy individuals is the efficiency of their aerobic system.  In other words, endurance.

Here's another fun graphic to help illustrate it:

I agree with this response. Over the last 4 years I have tried everything to running slower, faster, longer, 6-7 days a week easy, ect. I only run 4 days a week, sometimes 3 and between 15-20 miles a week at the most. For me doing sprint distances, less running was needed. I have gone thru a couple of injury periods (shin splints, stress fx,ect.) and personally my body doesn't do well with running consistant day after day.

Each person is different; you need to figure out what works best for you. Distance is important, and adding some speed sessions running off the bike have personally helped me. I had the same issue--would swim well, bike great, and fade off on the run. The past couple of years when I have focused on a good recovery,stretching, after each run, no matter how short , long, fast or slow-I started to see some improvements. I use to almost tread getting off the bike at T2 and runnig during a race; now I look forward to it. My run is no longer the fade-factor in a race for me. Helped me with a 1st place, 2- 4th places, and a 10th AG placing this year! Keep trying and do what works best for you.

Good luck

Actually, that's not what he's saying. The point was more to point out that there could be a number of reasons why a particular person is faster than another at a point in time. Considering that who you think you agree with is one of the co-founders of the "30 runs in 30 days" and is encouraging of people joining or trying it, I would think he's more for the easier consistent running. He's at 84 straight days of running, fyi.

Your race logs don't include sprint race results, but based on the data from your longer races, I'm not sure that I'd agree with your assessment that you're doing fine on the swim/bike and that it's the run that's holding you back. It looks like you're relatively evenly matched, and if anything your run might be your stronger event. Sure, you might get passed on the run leg in a race, but that's because there are some folks out there whose strengths across the 3 sports are seriously imbalanced. I pass loads of people on the run, but that doesn't make them poor runners; it just shows that I lose a lot of time on the S/B, relative to my run fitness.

As for the broader do-you-need-speedwork discussion, I've got to agree with the others that are recommending frequency and volume first. And I'm speaking as somebody who would love to do more speedwork if I could. But the frequent steady running sure does well for building speed over 5k+.