Ok need help solving this mystery lol.

For some reason when I unlock my driver side door with my key and I pull the handle to open the door
It locks it self back up.

The only way I can open the door is if i insert the key turn the key to unlock
Hold the key in the open position and lift the handle at the same time.

What would I have to check or replace ???

>

same 2 months ago, never fixed it or diagnosed it but it seems to be working like normal now

Likely you'll need to pull the door latch assembly out of the door, degrease it, and inspect for broken springs inside, if none found then re-grease, reinstall, and test.