So my toyota trucks brake pedal go right to the floor if you lightly press on it, but if you slam on the pedal, there's pressure in the lines and itll lock up the tires, I am at total loss. Any help would be much appreciated.

 

With the engine running, press the brake pedal... did you notice/hear any stumble in the engine?

 

Is your brake fluid at the proper level? Any visible leaks?

If so, those need to be taken care of as soon as possible!

If you don't have any visible leaks and the brake fluid level stays full, it sounds like the brake master cylinder's internal seals are stating to fail.

If you are light on the brakes, the seals allow brake fluid to slip by the internal seals, but if you step on the brakes hard, the seals seal better with the sudden force of hard braking.

I cannot say 100% that the master cylinder is bad, but your description sounds like a new one is in your future.

 

This means that your master cylinder is leaking internally, when you ease on the pedal the fluid is bypassing from one chamber to the other and not allowing pressure to build.
when you "stab" the pedal (hit it hard) there is enough instantaneous pressure build up for the seal conform to the scratches or pits inside of the bore and hold pressure.

 

old 87 typed faster than me!!!

 

Haha!

Usually it is the other way around.....

 

Sweet, thanks everyone, on the same topic then, I recently purchased a 1" bore master cylinder to upgrade before this started happening, but the plug on it is different than the plug in the truck, I thought I ordered the right year too.

 

What plug?
Brake fluid level switch?
post a picture
Also, what are you driving, all you have said so far was "Toyota Truck".
Is it a monster truck 4x4 or a low rider 2wd...?

 

I'm driving a 1986 toyota pickup, and yes I'm talking about the fluid sensor plug

 

Also when I am pressing on the brake pedal, no matter how hard or soft I press it, the engine has idle surge

 

That sounds like a vacuum leak from the brake booster. you might need a new one.
Also, regarding the fluid level switch on your master cylinder, without seeing what you are dealing with I'm guessing, but you may be able to use the cap from your old master cylinder or cut the wires and splice the plug onto the new switch, or unpin the connectors and re-pin the new switch into the old connector.