It sounds to me like the ears on your oil pan are bent and consequently the rim of the pan where the gasket seats is warped. Solution is a new oil pan. People tend to over torque the pan to compensate for the warp but this only cuts the new gasget.
The ears I mentioned above are torque "Stops". Once they are bent from over tourquing they must be bent back level again but if severly bent they crimp the rim of the pan. Once the rim is bent or crimped then the pan must be replaced.
1993 190E 2.3
2000 Toyota 4x4 Tundra