Hi all, I have a "restricted performance" issue that has been going on for awhile now. Check engine has always been on (since I got her about 4 years ago) due to a small evap leak, restricted performance started up about a year ago - comes on after the car is on for a couple of minutes in city driving, then goes off when I get her on the interstate, then back on when slowed back down. First suspicion is a vacuum leak but haven't had any luck finding one.
Codes are: P0171, P0174, P0442 sm, P0456, and P1000. She's got just over 120,000 miles on her.
Car runs great - no performance issues other than limiting out at 3000 rpms, which is why I've let it go this long.
Any ideas are appreciated.

thanks much!

 

Sounds like your small leak has increased.
After chasing mine, i found the eight gaskets.
Inside the intake manifold solved my P0171,& P0174 codes.

 

Mine turned out to be an external rubber hose leaking. Took it for a smoke test, instantly the leak showed itself.

 

By all means, DO eliminate any, & all other possibility's.
Before removing the intake manifold.
To replace those 8 pesky little gaskets.

 

thanks, any more info on which hose and where it's located would be appreciated.