Hi, p0301 is #1 cylinder and next is a checking the compression and if it shows lower than 120psi, your valve (most of case is exhaust vale) isn't seat well that need to remove the cylinder head (I hope it's not)
or if compression is normal then you have to find tha
vacuum leaks at the intake manifold (crack on it or gasket) or vacuum line(hose)broken on #1.
Good luck !
