91 S10 Jerky at crus'g speeds..??? Reader code help.

My S-10 starts to "jerk" when I try to maintaine speed. Almost as if I was in the wrong gear, but not that severe...though more than it should. I recently replaced the plugs, wires, oxygen sensor....but did not have any other "tune-up" (timing, ect.). The "service engine soon" light would come on after it would warm up, but then this was "now and then". I Went sand got a reader.
Two codes showed up. 35= idle air control can't be set to the desired RPM, or idle speed actuator problem (carbed system {which I have}). 44=lean exhaust indicated.
Anyone, help me with what this all may mean. I just reset the ECM test drove it...no lights, but it still gets "jerky". Not when idling....seems only when trying to maintane a speed wether 25mph...45mph......blah blah.

Thanks in advace
Shawn

P.S. Anyone in the Sacramento CA area with a older Chevy...if you get the service soon light, and don't want to spend the 30 dollars for the reader....maybe I can help out with at least using the reader.