Still struggling with my air pressure, keeps depleting

My compressor went bad so i got a repair kit for it and i have air pressure now but it only gains pressure when i accelerater it. When i let it idle the pressure starts going down. It goes from 120 psi to 60 psi in less than 20 minutes, i dont hear a leak anywhere though... im stumped, it cant be the compressor still could it?

 

Ok i figured it out, i think, but of course its a new problem, i adjusted the governor, played with it alittle till i got it up to 120 psi before it cut of, and i found a couple of leaks on sum fittings, now my biggest issue is that i used the same head it had before since the one i found for 300 bucks, instead of paying for mine at 900 dollars, did fit on the compressor just fine but had a different set up for the fittings on the truck...so i had to use my head which was alittle beat up on account of that the stainless steal plate/gasket had one of the sides that go over the piston brojen off and shattered into a 100 peaces and jammed into the pistons and head itself, i took all the scrap metal out and sanded the top of the pistons and the bottom of the head to make sure it didnt cut up that gasket.. well during reinstallation the fitting to the line going to the tanks, the tread on it messed up so i was leaking from there pretty bad...so bad that the pressure would drop from 120 to 60 in ten minutes.... so i rethread it and got a new fitting, i steal here a slight leak but not like before...

 

Oh its a 2007 Volvo 780 with a D12 volvo engine