jap speed

Hi all,
The engine has a problem where it can either run smooth or very rough. When it is just idling when its running rough, it either just wants to drop the rpm to the point to where it wants to die or the engine just surges from 1k-1400 rpm constantly. When I give it gas in the rough idle, the rpm gets around 2k then drops back down like it lost power then continues the cycle of going up and down if I hold the pedal at a constant position.

I checked the TPS and its giving off a perfect reading. The gas is good and its getting enough at the engine so i'm all out of ideas.The crank angle sensor is good so what is left that could be causing that type of behavior?

Any help is welcome.
Thanks

RotaryRocket88

iTrader: (7)

Surging idle is almost always a TPS problem or a vacuum leak.

The ECU advances timing over ~1000 RPM, so if your idle is surging, you will see timing jump back and forth with a timing light.

jap speed

Where could I find a good vacuum hose diagram? I have a feeling thats the problem but its wierd how it sometimes just runs normally without a hitch.