RPM''s on Perkin''s 4-108

[ABullard]

My Perkin''s 4-108 diesel engine will no longer run at more than 2000 rpm''s. I can not find anything wrong with it. This is the first time I have taken it out after changing the fuel filters and transmission fluid. I did have to readjust the anti-stall device after bleeding the lines because I inadvertantly loosened the whole device, not just the bleeder valve/

Any ideas as to why it isn''t operating properly?

Thanks.

Tony