Why can't am i getting worse at running

Too much running. Run every other day, once.

Do you eat a pre- and/or post- run snack? Sometimes when your diet is really good, it doesn't hurt to have a carb-based snack about 30-45 minutes before you run, or whatever is comfortable for you. Think Banana & Peanut butter, a few whole grain crackers and peanut butter, that sort of thing.

After a run, water of course. I found a recipe earlier this year that was Orange Juice, Mixed with Perrier or San Pellegrino (bubbly water) and a squeeze of lime was a great post-run pick me up. I've also been known to just eat my lunch after I run (I'm a mid-day runner). Search for articles on Runners World for more ideas.

I've been running 3 miles straight for the past 2 weeks but now i moved and i split up the 3 miles to different parts of the day

I still say over-training is the culprit. Your body is tired, and it's telling you so. Run every other day, one time.

I suspect too much running is the cause as well. But can't say for sure without more info.

How many months have you been running?

What's your average miles per week?

What was your progression up to that average per week?

If you can't run a mile then running 3 miles a day won't make it better. You'd probably be better off starting with C25K or some other run/walk program to help build up your endurance to 3 miles a day. Also running more than once a day is too much and you have to have rest days so your body and recover and get stronger.

I've been running for 4 years on n off again (CC and track) and to stay fit for the summer I've been running 2 miles a day but moved up to 3. my mile time has gotten a minute faster but i still understand why I'm not building endurance cause i wanna run more miles i can't believe last year i did the LA marathon and now i can't even run 3 miles

Huh. Ok so not a new runner as I assumed. Either way I'd just try to slow down take it back to 2.5 miles a day and see how that goes for a week. Also I wouldn't focus on time and distance at the same time. As distance increases your time per mile is likely to increase as a result of the longer total distance forcing you to take each mile a little slower. So while getting faster is nice. I don't like to do both, personally.

I've been running 3 miles straight for the past 2 weeks but now i moved and i split up the 3 miles to different parts of the day

Why bother with the low mileage twice a day? You're not getting out of it what you could if you ran once for longer. Not sure of your background, but with this method, I'm going to assume you're new to this and will say slow down, take more rest/recovery days, and quit with the bits and pieces running.

i split it up because i for the 1 mile i do HIIT but thats like twice a week and it fit my schedule better

You can't cannibalize your aerobic base-building and expect results...

I've been running 3 miles straight for the past 2 weeks but now i moved and i split up the 3 miles to different parts of the day

Why bother with the low mileage twice a day? You're not getting out of it what you could if you ran once for longer. Not sure of your background, but with this method, I'm going to assume you're new to this and will say slow down, take more rest/recovery days, and quit with the bits and pieces running.

i split it up because i for the 1 mile i do HIIT but thats like twice a week and it fit my schedule better

You can't cannibalize your aerobic base-building and expect results...

so how do i increase my distance to 4 miles

You just claimed to have run a marathon. Why are you asking how to run 4 miles?

I've been running 3 miles straight for the past 2 weeks but now i moved and i split up the 3 miles to different parts of the day

Why bother with the low mileage twice a day? You're not getting out of it what you could if you ran once for longer. Not sure of your background, but with this method, I'm going to assume you're new to this and will say slow down, take more rest/recovery days, and quit with the bits and pieces running.

i split it up because i for the 1 mile i do HIIT but thats like twice a week and it fit my schedule better

You can't cannibalize your aerobic base-building and expect results...

so how do i increase my distance to 4 miles

You just claimed to have run a marathon. Why are you asking how to run 4 miles?

I was truly going to try to offer something constructive but, this ^^.

Since it is getting harder to run instead of easier have you considered a medical issue? Maybe anemia or Vitamin D deficiency? What is your calorie intake? Are you fueling your body?

I've been running 3 miles straight for the past 2 weeks but now i moved and i split up the 3 miles to different parts of the day

Why bother with the low mileage twice a day? You're not getting out of it what you could if you ran once for longer. Not sure of your background, but with this method, I'm going to assume you're new to this and will say slow down, take more rest/recovery days, and quit with the bits and pieces running.

i split it up because i for the 1 mile i do HIIT but thats like twice a week and it fit my schedule better

You can't cannibalize your aerobic base-building and expect results...

so how do i increase my distance to 4 miles

You just claimed to have run a marathon. Why are you asking how to run 4 miles?

slow down the training. Run 1-2 miles at a time and when comfortable with your success - increase mileage. If you go to far to fast you burn out. More information as to how far, how long have you been running, how many miles a week ect. would be needed to do a just evaluation.

I've been running for 4 years on n off again (CC and track) and to stay fit for the summer I've been running 2 miles a day but moved up to 3. my mile time has gotten a minute faster but i still understand why I'm not building endurance cause i wanna run more miles i can't believe last year i did the LA marathon and now i can't even run 3 miles

Sounds like the issue is that you are training for speed instead of distance. Quit trying to run fast.
Whatever pace you are running your 2 mile stretches at, slow that down by 2+ minutes per mile and then go for at least 4 miles.
If you can't do that because your body insists on running fast, then run your 2 miles. Walk for 2 minutes, and then run again until you cant. Walk for 2 minutes, repeat, until you cover 4+ miles.