Put vinyl treatment like Armor-all or Son of a Gun along the vertical strip on the door sill plate and the bottom edge of the door panel. That will get rid of most of the squeaks. You can pull the A-pillar covers after you remove the strip on the door opening. Make sure the felt strips are in place and add to them if you think it'll help.

Sixto
91 300SE
86 300SDL (due soon)
81 300SD (for sale cheap)