so a couple months ago my 96 d1 with 160,000 miles was running really rough getting terrible gas millage and threw a couple of codes dont remember what they were I cleared the codes and started looking for lose or broke vac lines and noticed that separator to intake hose was closed on its self so i toke it off and the rover was running alot better and getting about 3 mpg better left it with no hose and then i got a 1178 code so i thought i should put a new hose back on but where i live its a thirty mile drive to get any parts for a disco so today i went to ace hardware and got 1 piece of 5/16 fuel line and 1 piece of 3/8 fuel line one 3/8 to 1/4 plastic reducer and one small hose clamp

put it together and now my rig runs so smooth hoping for better mpg's to and waiting to see how long til i get another code

 

You can use any hose you want for the PCV hose, I have old lawnmower fuel line on mine, been on there for 4 years.
Just a FYI you were sucking unfiltered air into the engine by driving with that hose off of the intake.
You are fine with the hose that you used.
Make sure you remove and clean the oil separator every 6 months, use cafrb cleaner to clean it.

 

i cleaned the separator out yesterday it was really bad next on my list to fix code 1317 abs rough road line low fault detected

 

Good luck fixing that ABS code.