vacuum leaks are a pain with all the hoses we have under the hood right to the ecu in the trunk. Easy to find with a smoke machine.connect the hose to one intake port and see all the smoke coming out af your cracked or disconnected hoses. Cheap machine can be find everywhere they sell party stuff. Hope it will help someone in the forum Yvon 89 xjs conv.

 

I have had far better luck using the STFT's and a scanner tool reading real time data. Spray propane or carb cleaner on all the spots you suspect of causing the vacuum leak and watch the STFT's. They react very quickly and so you can pinpoint the problem.
.
.
.