Most runners tend to stride out too far due to a low steps per minute (cadence).
The majority of social runners have a step count of 150-155 steps per minute. This results in a lot of heel striking. Aim for 175-180 steps per minute. The aim here is to transition from a predominate heel striker to a mid foot lander.
You can work on this by downloading a metronome on your phone a free one and set the beat to 175-180 and put some headphones in. Run at your normal pace but keep up with the step count.
This is a good start to changing the running technique. In regards to shoes, I would look at this site find your current shoes (the old ones) and see what % they are and try and get a slightly less % shoe (more minimalist). I am a fan of less support and cushioning (and it matters for fuck all if you mid foot strike).
Load management is important as well. Don't increase more than 10% at a time. 5% is slow and steady. That 5% can be increasing either time/distance/pace but only do one of them at any time.
Start a 3 week program of foam rolling your ITB.
To make it managable start off with this and add one roll each day.
Day 1: 3 sets of 3 rolls each leg.
Day 2: 2 sets of 3 rolls and one set of 4
Day 3: 1 set of 3 2 sets of 4
Day 4: 3 sets of 4
and so on until you get to 3x10. After that point just do 1x10 after or before a run for management.
The sets of 3/4/5 will hurt lots 8/9/10 should be all good. Don't skip a day. Do it for 2.5-3 weeks should be feeling good.
Work on this for glute stability, make sure your foot is dead straight. Knee over middle toes. Don't go for depth go for control. This video gives an average example.
Also work on some supine bridges. Can start with two legs on the ground with both arms down. Then go to no arms supporting.
Then single leg (control pelvis don't let it rotate) with both hands down. Progress to one hand down then no hands down. Further progression put your heel on a foam roller (really works hammys) then further is put leg on swiss ball hold position and roll the ball in and out.