Nissan Repair: 2001 Nissan Sentra sputtering, nissan sentra, return spring

Question
Thanks for the quick response, and sorry for the late follow-up question (Christmas is pretty hectic).

After cleaning the EGR, I let the valve close and tried to blow through it and it seemed airtight, so I don't think it is stuck open.  I also cleaned out the TB -- removed it from the car, fully disassembled and cleaned every nook and cranny.

It still has the same symptoms after this, but now has some new ones.  Now, when I make minor throttle adjustments when driving (easing on/off the gas), the car jerks, very similar to how a car jerks when driving in first gear and the throttle is really touchy.  It does this at slow and highway speeds.  I'm also noticing some white smoke coming from the exhaust -- it's not spewing out heavily, but it is noticeable.  It also seems like it is idling higher than usual, but I still need to check this with my scanner (the car has no tach).

A couple of days after cleaning the TB, I got MIL code 0505 - Idle Control Malfunction, but a couple days later the SES light turned back off.  

Could the Idle Control Valve cause all these symptoms?  I'm afraid to pay ~$150 to replace it just to find out that it's not the problem.

Is there anything else I can check for these problems?  Is it probable that my cleaning the TB created these new symptoms (the Idle Control Valve assembly had a return spring that I'm not completely sure I re-installed correctly)?

BTW, could the fuel filter cause this problem?  I've checked under the car and couldn't find it, and no local parts store lists a part # for it.  Does a 2001 Sentra even have a fuel filter?  If so, where is it located?

Thanks for your help with this.  Your advice is VERY much appreciated!

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Followup To
Question -
My 2001 Nissan Sentra 1.8L sputters at idle and when accelerating from low RPMs (i.e., 40mph in 4th gear).  It has 98,000 miles on it.
At first it almost stalled when idling.  The SES light was OFF, but after letting it idle for a while I got code 1402 - EGR system.  I cleaned the EGR valve.  This improved the problem, but the sputtering is still very noticeable.  The SES light has not turned back on.
 I cleaned the EGR valve a 2nd time and replaced the spark plugs.  No change; it seems to get a little worse every day.

Not sure if this is relevant, but at one point I removed the EGR solenoid but left it plugged in to watch it operate as I moved the throttle.  When revving the engine, the solenoid motor would advance about 1/8 turn, then immediately move back 1/4 turn, past the point where it started at (when backed in all the way, it would just click).  Is this normal?  Is the solenoid possibly not advancing enough?

If this is not an EGR problem, what else can I check?

Thanks for your help!
Answer -
Steven,

The EGR looks to me to be bad.  If you block the passage and run the car does it run properly?  If so replace the EGR.  If there in no change then the valve is not the problem and you are probably looking at cleaning the throttle body.

Answer
Steven,

The fuel filter is in the tank with the pump and sending unit and if the pump is bad the assembly gets replaced.  Also, the filter is supposedly lifetime and does not have to be replaced.  I have a 350Z and the pump and the filter were replaced for a condition similar to yours.  The regulator was defective and it plugged two injectors when it went out.  It is in the tank too...