Originally Posted by lk21joker

It sounds like you have a problem with the valve timing. It's becoming inefficient for the air coming in and out when the valve is not at the correct timing. I suggest you have it adjusted at a bodyshop. It happened to my old 94 ex accord and 97 civic, luckily my friend is a mechanic and he fixed that for me, both cars.

Another case is the engine knocking, if you use lower octain gas than suggested in the manual, your engine will suffer a lot of knocking, and it will damage the engine over time. Just try higher octain gas and see what happens