Sometimes injector problems go beyond "clean or dirty".
Like any mechanical device, a fuel injector can wear out or even be defective from the factory. No amount of cleaning will resurrect an injector in that condition.
We are pretty picky about the tolerances that we allow in our injector service. Many times we'll have somebody that sends in their injectors after an engine failure looking for a cause. It might only be 1 or 2% lean on a single injector that made the difference. We're not gonna gamble your motor over that.
BTW, Bosch will no longer produce the 036 injector that's used on the 260, 280, and Drag Motor after the middle of 2007.
The ones that we've got from them lately have been of lesser quality too.
Out of the last 100 new ones that we've bought, we rejected 39!!