Rene, check out Mike Ponte's homemade FI cleaner at:
http://www.mikeponte.com/volvo/injectors.htm

I took this out of the FAQ because it seemed that motivating folks to have their injectors professionally cleaned, tested, and measured was the way to go, not the hazardous homebrew technique. But have at it if you must. Try a local shop to see what they charge: most are reasonable. The need to clean, beyond a bottle of Techron, is much diminished with better detergent gasolines.