How to find vacuum leaks

[Larry C Leung]

Well,

Finally got my coolant expansion bottle, installed it and while waiting
for the cooling fan to come on during the bleeding, I decided to do the
dipstick test to see if some of the stumbling and hard starts might be
vacuum related. Well, pull the dipstick, it stutters, loosen the oil cap,
stutters worse, lift the cap, it finally stalls. Soooo, I have a vacuum
leak. The problem, I can't tell where. The hoses I checked so far look
good, I know I do need a valve cover gasket, but I can't tell if it's
something else (it seems from the dipstick test that the leak is likely
more severe than a mildly seeping valve cover gasket!). I recall someone
on the list saying something about propane, but I'm not so sure what they
said...

LL - NY