I guess you ain't so sure about the racing line yet? cos you seems to be heading into the unknown when you steer into a corner, sometimes you steer too late and have to correct understeer, sometime too early and you have to slow right down. I think you do understand the consequence of steering too much mid corner, comparing lap 2 (which is completely ragged) to lap 4, you know you should steer smoother, however there are still places when you try to recover the car that your suddenly movement cause problems, for example at the slow chicane, I think it's down to lack of experience in anticipating what the car will do.
The most obvious thing to work on is though, find out the right line first, you start by focusing on where you brake - sometimes you brake in the middle of the track, sometimes a car width to the edge, you should brake using the full width of the track and allow yourself a wider line into the corner, which allow you to carry more speed. So pay attention to where you brake every time,find your braking point when you are on the straight and anticipate what you should do.
When you are braking, avoid any lock ups, cause it destroy what you have been setting up,you will be forced to correct it and miss your ideal line. Then, find the apex of the turn, move to it precisely and once pass it, accelerate decisively. On the fast corner it's generally alright, there are space for more speed but that's for later. For the slow chicane though, you tend to stay too close to the apex and have to slow down a lot, because you are running a very small radius compare to what you should be doing, and to make up the lost speed you jump on the throttle too hard, upsetting the balance yet again, you should brake on the right side, do most of your braking in the straight line,then cut into the apex WITH your mind set on the exit of it, meaning that you should find a line that allow you to stablize the car right after the apex,to be prepared for the right turn ahead. you will have to control the sideway momentum and steering angle throughout the sequence in the turn, it should be rapid at the entry, then gentle near the apex.
the last turn in similiar,your apex is too early, because you hug the inside too much when braking, again brake on the right, turn into the apex with more speed and compare to your current run - try to complete more directional change before the apex, because after the apex you want good clean acceleration, so you will prefer the car to be straight and spend less grip used for turning, hence you should do most of the turning before the apex and less for the exit, there's a balance to catch in what is the fastest way around. But it shouldn't be hard to notice which way is faster.
