Dearest engine wonks,

I have a yanmar 2gm20f with sd20. When it's cold and it comes under
load (eg. the alternator starts developing more than 20 amps) it is
unable to hold its rpms. Typically it runs easily up to speed but then
as the load kicks in it drops back down to idle and then revs back up
past the throttle setting and then drops back down again. Sometimes is
stalls. Once it has gotten warm it runs like a top. There is no
visible smoke. I have:

replaced the fuel and both fuel filters,
replaced all the washers on the fuel lines and checked for leaks,
taken the injectors to a shop to be checked.

Now, I don't know what to look at next. Any ideas out there?

Thanks,

-- Tom.