Not what you want to hear, and granted, its my own personal experience............
Our wallpaper was up for God only knows how long.......we bought an old house.........and we couldn't EVER get all of the residue off after stripping the paper.........and I tried just about every product on the market.
If you are going to re-paint, you might consider re-texturing the walls..........that's what we did, and it worked great.
Here's my personal experience from buying a house last year that had luminous adhesive stars on the ceiling in both of their kid's bedrooms. Scratch off the sticker, wipe off as much of the adhesive as you can with warm water and a sponge. Let it dry, KILZ the entire area (ceiling, wall, whatever), let the KILZ dry and repaint. Time consuming, but the only thing that we came up with to cover and have uniform paint coverage of the area.
