Bro, tell us what you've done to your braking system, when you did it, and what brand stuff you used.
I suspect you've got dirty brake fluid. Piston bleeding will probably help you loads. However, before you do that, test your mc (master cylinder) first.
Mc test :
1. Hand and gearbox brake at park.
2. Start engine. Shut off after thirty seconds.
3. Pump the brake pedal fully and repeatedly. You should get at least 2 full pumps before the pedal suddenly becomes hard.
4. Hold the now hard pedal with full force for 1 minute. See if the pedal moves down. Pay close attention, put your other foot next to the one on the pedal to assess movement and make sure you have good light. Even slight movement down over time is not good.
5. (after 1 minute of holding hard), While holding the pedal down, start the engine. In a few seconds the pedal show go all the way down and should move down evenly and not sharply or slowly.
6. Repeat 1-5 above until you are very sure of your results.
7. See if your brake fluid is going down.
The thing is, your mc can be screwed even if it leaks very slightly.
A leaky mc will reduce the braking force to the pistons and reduce the speed at which that force moves from the mc to the pistons. This will of course mean lousier brakes.
If this test proves a suspect mc, change to a new one and do piston bleeding when you install the mc so that you only do one round of bleeding. Before installing the mc, make sure the mechanic bench-bleeds the mc. Please see youtube on what that means.
