NX Hesitating on partial throttle

[dlp]

Got a '93 NX 2K with 110k miles on it.  It's starting to "hesitate" under
partial throttle, mostly between 2500 and 4000 rpms in 2nd and 3rd gears,
although it occasionally does it in other gears in the same general RPM
range.  It almost feels as though the throttle is rapidly being closed and
opened (I can duplicate the feeling by slapping my foot on and off the
pedal), and sometimes the car will buck badly.  If I floor it, it will
always pull through the "hesitating" area and continue with hard
acceleration.  This problem makes it very hard to drive the car smoothly in
city traffic. I've been through 2 different tanks of gas now, so I don't
think it's just a case of bad gas.  My first thought is that the throttle
position sensor might be developing a "bad area", but wanted to run it by
the list to see what you guys think before I start digging into the service
manual and ordering parts.

Thanks,

Doug