What brand O2 sensor did you use?

edit: Unlikely but it could mean you have bad injectors causing a lean condition, or a MAF problem. Have you ever cleaned the MAF sensor?

DTC P0131 = HO2S Circuit Low Voltage Sensor #1

(The following is from the FSM)

Check for the following conditions;
- Heated oxygen sensor wiring. The sensor pigtail may be routed incorrectly and contacting the exhaust system.
- Poor PCM to engine block grounds. refer to wiring diagram.
- Fuel Pressure. The system will go lean if pressure is too low. The PCM can compensate for some decrease. However, if fuel pressure is too low a DTC P0131 may be set. Refer to fuel pressure test procedure.
- Fuel Injector(s) Refer to Fuel Inj Coil Test
- Vacuum leaks. Check for;
disconnected or damaged vacuum hoses.
incorrectly installed or malfunctioning crancase ventilation valve.
Vacuum leaks at the throttle body, EGR valve, and intake manifold mounting surfaces.
- Exhaust leaks
- Throttle body inlet screen, check for damage.
- MAF sensor. Disconnect MAF sensor. If the lean condition is corrected replace MAF sensor
- Fuel contamination

There is much more in the FSM regarding this code, too much to type here. There is a lengthy paragraph on measuring voltages with a 10 megohm digital voltmeter. Need to be able to read in the mV range.
Suggest getting a copy of the FSM, will help you in the long run diagnose and troubleshoot not only this problem but any future problems.
HTH

thanks alot for all the help, had my dad take a look at it and it turned out to be that the cause was my idle being to low .

Idle too low... so was it the IAC?

Idle should be controlled automatically, so unless you had a bad idle air control motor, that doesn't make sense to me.

idk theres a little screw in the back of the throttle body that increased the tension on the the throttle cables, im not an expert or nething but i turned the screw a little my idle increased the roughness seemed to level out.

So... i have this dumb code for my O2 sensor DTC P0131 = HO2S Circuit Low Voltage Sensor #1...

I replaced my O2.. and it had the same issue of rough idle.. and when im going down a hill the rpms surge from 200rpms to about 1100 rpms.. so i got another new one.. SAME PROblem... and than i went ahead and i unplugged my o2 all together so that my car would run normal.. so right now i am running open loop.

Its fixed... thanks for the input.....

Deek,
I think it was 24 hrs 8mins.
But still, @ 02:40 not too many people looking at the board.

Oh you are right. Whoops.