You mention that you sprayed some WD40 at the "lever" area. Is this the area on the lower left side of the driver's seat? If so, I would try to spray the trunk latch (in the rear of the trunk).
I think that I have also had the same problem that you describe, although only intermittently. The trunk opens fine, but then when I try and close the trunk lid it doesn't stay locked. I have not tried to permanently fix this yet because it seems that when I jiggle the trunk latch (on the rear of the trunk) it seems to go away for a while.
Let me know if you find the solution.
1996 Contour SE Sedan 4D (Royal Blue)
Duratec V6 2.5L 24-valve DOHC
Automatic
75,000 miles
No Mods (unless you call the DMD a mod)
Replaced EGR valve (gunked up), EVR (EGR VR), PCV valve, and evaporative emissions hose (cracked).
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