Due to a 2600 mile move, new job demands, and other excuses I have not sailed me J/30 in about 8 months. I have been faithfully running the engine every 3 weeks for about 20 minutes. (battery charge and just running the thing)

It has been progressively harder to start with the start position of the throttle being more and more forward. When running the engine I have been running the RPM high before shut down to try and keep the injectors clean. This weekend the engine just died when I put it in idle. I restarted and ran the the RPMs above 2500 and I got a lot of grey smoke.

Any ideas?

I am thinking injectors. I am a diesel engine novice and had a few questions.

How tough is this job?
What is recommended for cleaning the injectors?
Will an additive fix the problem?
Will I need to bleed the system after cleaning?

Thanks!