slicshoes

the problem is that when i start my car and drive away as soon as the rpms hit 2000 it seems like it hits a cut off and the idel drops back down to 1000 or when u leave the car in neutral and rev the motor it does the same thing but inder hard/moderate exceleration it wont do it for some reason/ also after the idel drops i do not have any throttle response unless i press the pedal down like and inch and then it surges forward
the car ran fine untill my friend and i corrected the timing issue and realized the IAC was never hooked up/ we corrected that also but ive had nothing but problems with it since
any advice or insight will be appreciated

so my lsvtec i think isnt getting the rite fuel pressure to the fuel rail and ive in stalled a new fuel pump/filter and siphon in the tank.also ive replaced the throttle cable and cable stay
also i thought that it mite be the tps so i bought a new one from omni power and intatlled it and the problem remains/ i also noticed i dont have a block breather on the back of my block could this be the problem
_thanks