vacuum leak detection

so i have a suspected vacuum leak on a 3.4 Camaro engine. cold idle (with good IAC) is 900 RPM. as the engine warms up/during drive cycle, idle increases to a max of 2000 rpm. will not come down. after shutdown, still warm, idles 1500-1700.

im thinking vacuum leak. also little rich, and throttle response is kinda soggy. not exceptionally horrible on either (like it was when I started in on it), but noticible to me.

ive never had any luck doing the spray carb cleaner trick, and holding a giant thing of propane around hot headers hiven me the willies. what other options do I have?

also, anything else that could be amiss that im not thinking of?

Smoke test. Maybe use a smoke generator like the bee keepers use.

Cigar! If you don't imbibe, get a friend. It works!

Yup, smoke machine.

Starting fluid works way better than carb cleaner, though you have to use the straw from the carb cleaner.

yup. no vacuum leaks. and im now out of ether AND propane.

but after switching out the ECM for a known good one, all my problems resolved.

damn engine swaps.

and I saw the cigar trick on google, but dodnt think it sounded like it would actually work. whats your procedure?