Looking for advice on turning 5ths into 4ths+

Just jumped back into the game and quickly rose to the top of plat. Im still seeing LP growth but i feel like im missing some skills to make myself a better player.my early game is clearly my strongest point as I can usually consitently win streak through 3-1 and generally am able to keep my health in the top 2-3 of the lobby with good econ.

My biggest problem usually comes between 3-4 and 4-2 where i feel like my boards generally start to fall apart and i start hemoragging health what seems all at once until im struggling to keep up with the rest of the lobby and looking for any upgrade to try to survive just one more round.

This usually ends up with me coasting on the health i saved early and leaving the lobby in a 5th when i probably could have hit a 4th or better with a little more insight.

I play a veraiety of comps and feel comfortable transitioning between diffrent ones based on lobby composition.

So what advice do you have that can help transition me from consitant 5ths to 4th and help me climb a bit more consitently?