2003 Vibe Possible vacuum leak

[Dewhittier]

Hi. I have a 2003 Vibe that I bought new and has always ran great until a few months ago when I had to take it tires plus because I was on a road trip and didn't have any other options. They put in a new serpentine belt and tentioner and it has been running terrible ever since. I replaced plugs, coil packs, MAF sensor and other things to get it running better because I was getting error codes pertaining to that issue. Now it's running better but it doesn't have much power and the gas mileage is pretty poor I'm thinking that it's a vacuum leak because I can hear a slight hissing by the driver's side front wheel and when driving and excelerating the hissing gets pretty loud. I have tried tracing every line and even tried hooking it up to a smoke machine to try and track it down but have been unable to find anything. If anyone has any suggestions on how to move forward or what it might possibly be please let me know it would be greatly appreciated. Thank you for your time and have a great day and take care and God bless.
P,S For more information check out my other post
(A tick while in overdrive)
Thank you again for your time.

[andrewclaus]

Engine vacuum is highest in idle, lower when throttle is open, so it's probably not a vacuum leak if it's louder when accelerating.

[Dewhittier]

Thank you for your reply.
Any suggestions on what could cause the jet sound while driving?
Thank you for your time and have a great day and take care and God bless.

[joatmon]

I thought a long shot would be a small exhaust leak cause by forced air escaping upstream from a clogged catalytic converter but I doubt that would manifest itself on the drivers side, and can't see how replacing a tensioner and belt would cause that. Also hard to imagine what a shop might do in replacing those things to mess with the vacuum lines, if that work was the only change that coincided with the symptoms appearing, if it was actually something they did to causedthe symptoms.

Is the air filter clean, and that whole assembly properly attached to the throttle body?

Maybe use a piece of hose as a mock stethoscope to try to really narrow down the location of the noise source

[Dewhittier]

Thank you for your response.
I replaced the filter and checked to see if everything was installed properly and it was.
And the hose is a great idea I will try it and hopefully it will lead me to a solution to the problem.
Thank you for your time and have a great day and take care and God bless.