u/Beneficial-Yam3597

Hissing sound when idling and when it gets up to operating temp. It was a lower pitch a week or so ago but I did hear it back then but couldn’t pinpoint were it was. What is that 90 go to? Is it part of the fuel rail or something? Also it rough idles and has inconsistent acceleration which I though was the leaking intake manifold that I have ordered. Also it has 134K miles on it. Any advice is appreciated. The accelerator doesn’t like gradual acceleration so I have to tap it to get it up to speed. No check engine light but it feels like a misfire.