Vacuum leak

06 with 4.0L engine. The truck has 131k on odo. Last week the truck developed a whistling type sound. Vacuum leak? I tried to find the problem with some carb spray but had no luck. No codes and the truck is running fine. Do y’all think I’m on the right track? Thanks for your thoughts.

 

This may or may not apply to your situation:

https://www.tacomaworld.com/threads/weird-whistling-sound.496054/

 

Had a worn O-ring on a brake booster do that to me once. Was on a Ford though.

 

You could try a smoke test?

 

Thanks for the replies. This whistling noise, for lack of a better description, is audible as soon as I fire up the truck. It changes a bit as I start to drive and at speed can't be heard at all so I don't think it's related to weather stripping or anything like that. I'll give the smoke tester a try and see if it leads me anywhere.