Vacuum line

I wouldnt think so diesels do not have manf. vac. as gas engines. the atl. I think drives a vac.pump to provide an vac. in the crankcase for emissions.but my tractors do not have this setup .hopefully someone will chime in who has a newer model.

Have you checked the fluid level in the injector pump?  Most of these Chinese tractor injection pumps take eight to twelve ounces of engine oil to keep them lubed.  They use either a dipstick or a witness plug to determine the correct level.  This should be checked every time you change your oil.  If the IP runs low on oil it could cause the governor to respond sluggishly.

jonesgrove, please explain more about the vacuum line that you say goes to the crankcase.   Normally the pump on the back of the alternator operates an EGR bypass valve near the top of the engine.  What tractor do you have?  What engine?  

There should actually be three hoses I believe. 1) Oil supply from gallery.  2) Oil drain back to crankcase. 3) Vacuum line to EGR valve.

jonesgrove, now we a a bit more clear.  That line is a oil line not a vacuum line. You might want to check the vacuum lines near the top of the engine.  Look for the Chinese rubber to be split etc.   I had two new 454s that had slow response on one because of a split hose  and a traveling miss on the other because the vacuum hoses were connected backwards from the factory.