Hyundai Repair: 2000 Elantra, air flow sensor, needlenose pliers

Question
My 2000 Elantra runs a little rough.  When idling the RPMs surge, then fall below normal idle, then normal again. Sometimes it drops enough to make it stall.  Also, during highway driving, 60-65, it will buck (same thing I think, tach fluctuates).  It seems to do it more with light throttle pressure when cruising.  I didn't notice it on cruise until recently, now I see it then too.  It's done this since I bought it used a long time ago.  If it stalls, it usually starts back up but sometimes takes a little more cranking or waiting.  Engine light never came on in the couple years I've had it with this problem. It did come on recently for P0440, but I reset it and haven't seen it since and that was only recently and I don't believe it was bucking when it came on.
Any ideas or suggestions on what to look for?  Thank you.

Answer
P0440 is an evaporative system issue, so it shouldn't be realted to any stalling or running rough, unless it occurs immediately after starting the vehicle.  

I've seen the symptoms you describe a couple times (also with no diagnostic trouble codes) due to a poor connection at the air flow sensor.  This is still quite a bit of a longshot, however.  You could try twisting each of the pins on the sensor a little bit (with needlenose pliers) to ensure good firm contact with the terminals in the connector.