huge power loss, help!

[mac_daddy]

i have a 1990 240sx with a stock ka24e 5sp. it has been intermittently bogging down. sometimes i have all the power sometimes it doesnt. whenever i come to a stop it dies or the idle will jump around and drop below 500rpm. i recently change the plugs, wires, cap, rotor, re-timed it, and a new fuel filter. just last nite i was driving my gf home and all of a sudden the car bogs and wont go past 4000 rpm, i put it in neutral and rev it and it still wont go past 4000. im completely stumped could it be a fuel pump? tps? AICV? idk. ive searched and cant find anything similar.any help?

[mac_daddy]

also forgot to mention that i have a check engine light and threw a code 55 and everytime i rev it and let it frop back to idle it makes a hissing sound.