You would know if you had a Power vacuum links of the brakes. Hard pedal. Run it by
a brake shop, have it looked at. Not good to have a brake problem.

Most modern cars have Traction or stability control. you to turn these functions off. If you see what looks like the rear view of an old sedan followed by some squiggly lines on the road behind it, then that means your stability control system is either partially or fully off. This means one of two things has happened here: Either you turned the function off because you wanted to do some sporty driving turn it back on.. It's safest to let the computer think about traction for you, so find a way to get it.

 

Never had a hard pedal, it's actually kind of the opposite... don't have brakes engage until like 4 inches down. Then they engage real well. I've asked about that on some FB groups and people tell me that travel is normal apparently.

Still curious about the vacuum leak though, not sure how I'd figure out where it's coming from. I've poked around the whole engine bay, couldn't see or feel anything obvious. It's hard to narrow down where the sound comes from.

 

How many mile are on your 453?

 

Almost 18k

 

…any vacuum leak will create havoc on engine management…

jetfuel…specially turbo

 

I know it's not good to do (obvious fire hazard) but I saw a crazy idea online where someone started up the engine cold and sprayed carb cleaner around various spots to see if the engine would rev up.

Didn't have much luck. Tried it two different times throughout the day. Everything seemed happy.

The hiss goes away the second I step on the gas, comes back immediately at idle. I poked around everywhere I could reach from above... still need to borrow a jack and stands to look from below.

Definitely sounds like it's coming from the back-middle where is hardest to reach or see.

I'd love to hear someone else's NA 453 engine compartment for reference... surprisingly there isn't much online for me to compare to.

 

mine sounds the same