1992 Honda Accord LX

Okay so I've had brake problems for a few years. My car just will not stop properly. The front brake pads begin to burn after a little bit of hard braking. The stopping power just isn't there, and I have to make up for it with mashing the peddle and/or e-braking slightly. I've had 3 different sets of calipers put on cause they lock up or explode. I've had 2 different sets of rotors. God knows how many sets of pads, including a set of hawk pros that just barely made my braking anything near respectable (and only for 10k miles). Every component of the system has been replaced front to back in the last year save for the brake booster. My mechanic has looked at it like 5 times and keeps telling me there's nothing wrong. Clearly there is. There are no fluid leaks in the system. Everything that's on there now has been installed by a licensed mechanic, yet it still continues to function at PERHAPS 60% of what the braking power should be.

Brakes are not hard. Conventional logic dictates this. Yet a fully licensed automotive mechanic cannot seem to fix it, much less myself.

Some theories:

The rear drum brakes could be not contributing for some reason. When I last did the rear brakes, I'm pretty sure there was a star adjustor, so it should be adjusting the shoes automatically. But if the rear drums were working properly, under hard braking wouldn't they be fully engaged? If that were the case then pulling my e-brake would add little effect to my stopping power. When I use it now, it contributes quite dramatically in stopping my car. This would also explain the overheating of my front brake pads, due to the fact that they are being given more load than they were designed to handle. When I had hawk pros on there, they almost never burned because they were kick ass pads, but they did burn under insane braking conditions.

Nissin vs Akebono calipers. I don't have a clue what the difference is, and I don't think my mechanic did either. Perhaps I have the wrong type?

Master cylinder cap is slightly loose. if you pull on the outside edge of it, it lifts up so that there is air exposed to the cylinder. Must the master cylinder be 100% completey totally absolutely airtight to function properly? I'd say when you lock the cap in its probably like 95% airtight, judging from the amount of play.

Malfunctioning brake booster. My mechanics told me time and time again that they ran vacuum tests on the brake booster and that it was still good. If i'm not mistaken, the brake boosters for this vehicle draw vacuum from the engine's intake manifold right? I have wondered if perhaps a vacuum leak in the intake manifold would subsequently cause a lack of vacuum in the brake booster.

Feel free to eliminate any of those theories or actually provide a solution to this problem. With my brakes in such deplorable condition, it is proving difficult to sell this car.