New Holland L781 repower/rebuild Deutz engine

I have a new holland L781 skid steer that has the Deutz Air cooled engine that runs extremely rough, and has lots of blow by, i bought it like this earlier this year (cheap) and have not been able to correct this rough running, changed all the filters and checked all the lines for blockage and restrictions and replaced the fuel pump, I do not have the special tools to replace the injection pump. My question is does anyone know of a shop or dealer that sells/rebuilds these F3L912 engines or maybe even a used one, I have found them online and 7K is way out of my price range. or maybe even a replacement engine that can be dropped in fairly easy.

Thanks
Scamp

New Holland L781 repower/rebuild Deutz engine