1990 bronco 2

i have a 1990 bronco 2 2.9 L i have gas coming out of the vacume line on the side of the fuel pressure reg.witch usally means the reg. is bad.I have replaced the reg. twice in two weeks it will work fine for about 50 miles and then starts shooting gas out of the vacume line.There is vacume on the line all the way to the reg. What elese could cause this to happen?I have pulled the tank to check for trash and it is clean and i have a new fuel filter.
thank's db554