PF2 bring this close to perfection. Want to move 3 times? Sure! Want to Move, Jump and Attack! Go for it! Spell and Sword? Why not? 3 attacks? Of course you can.
I like the PF2 idea of 3 actions.
But I would go for 6 action points per turn(AP). for 6 seconds that the turn lasts.
then you can have 2 AP for a single attack. And 3 AP for dual wield attack.
Or 3 AP for "power attack"
Movement can be less, 15ft per AP.
Casting spells can be anywhere from 1 to 6 AP. Current bonus action spells could be 1 pt, while regular Action spells can default to 3 AP.
Then metamagic can add X amount of AP to casting spell to add effects or to remove components(V,S,M).
haste spell can increase AP pool by 1-3 points, depending on spell level, same as Slow,
having less AP is also good option for some Poisons, Diseases or exhaustion levels.