There really is not a cleaning service for the injection pump. If you remove it and send it in, it will most certainly be determined that it must be overhauled. An overhaul is in the range of $2,000 now. It is a good idea to rule out other issues before performing a pump overhaul. The pump idle mixture is not hard to adjust, but other adjustments become more involved. Check linkages and throttle valve settings, etc. . You might also check the injectors as the poppets tend to leak often due to corrosion from time. Even the injectors are now expensive but an overhaul shop will expect them to be sent in with the pump and defective units replaced before they set up the pump anyway.