I have an l98 TPI and this winter over the rebuild some of the plastic vacuum lines broke, we replaced them with rubber lines. but its seems atm that i have a large vacuum leek coming from somewhere. are there usual spots where I can check that usually leak? is it okay to replace the lines with the rubber? and is there any diagram for the vacuum lines on this setup?

(I suspect it is a vaccum leak because my idle isnt working right, and my tachometer flutters and its affecting the transmisison because it wont shift right)