past couple of days, i've noticed on my 98 civic si that when i press on the brake, the pedal is much stiffer then before and the braking is as smooth when slowing down. any ideas what's wrong? i also feel the gas pedal is abit more stiff as well and loss of power

 

Check the vacuum line running to the brakebooster.


Disconnected brakebooster would give you a much harder brake pedal in a short amount of time

 

you probibly have multiple problems there. either that or your floor mat has pushed up enough to make pushing the pedals hard. (common problem)