getting new injectors might be both simpler and cheaper than having them cleaned, the materisl that the injectore are mde from does actually eropde after years of usage from the gasonile flowing thru them, nothing can be done to avoid this. a great place ive found to buy autoparts for our mercedes cars is
www.expressautoparts.com they are cheap, deliver fast and if you spend over $50 in parts(not hard on a mercedes) you get free shipping.