Steve- you may need to remove your door panel then clean & oil the rods from the bottom of the handle unit , to the latching mechanism.
Once the door panel is removed, there is a plastic cover over the rod (connecting the handle to the latch) that must be removed, by removing 2 screws from the door jam(top). Basically simply- if I can do it, surely you can.
This should remove any resistance from the inside. I used a lithium based spray grease that - so far- has worked really well.
My drivers door handle sticks also, but the door latch works everytime. My problem is different , i.e.- the "flapper" part of the handle is rubbing on the internal side of the handle. Just havent had time to take a Drimmel tool to it to "file" the flapper a mm off.
Hope this helps, Mike J.
:dance