moorzpheen

ok....I did a post awhile back on replacing my intake manifold on my '97 GT.
Well I got the the new one on & everything else hooked up but when I fired her up she has a REALLY rough idle.
It idles fine when I first fire her up but then she will drop to 500 rpm & then back up to 1000 rpm. That jump goes on & on & on. It almost gets to the point where it's gonna die then jumps back up to 1000 rpm then back down.
I also noticed a sucking sound coming from the rear of the manifold on the driver's side. From what I can tell it's coming from my EGR valve on my plenum or from the fuel pressure regulator which sits right by my EGR valve. On a another note it could also be the DPFE sensor thats bolted on my firewall right by my fuel pressure regulator, or.... I could've not tightened down the rear bolts to the manifold on that side. I also thought that it could be a vacuum line but I don't see any problem with the vacuum lines. I also think it might be my Electronic Vacuum Regulator.
If any of this sounds right PLEASE let me know. This car means alot to me & I'd like to get her back to the way she was very soon!!

KeviN...MoorzpheeN

Pohatu18

Sounds like a vacuum leak, is the line behind the upper plenum(vapor canister purge valve) hooked up?

00perfredgt

+1 on vacuum leak. Make sure all the hoses are hooked up. Check for cracks. Did you tighten intake bolts in proper sequence and torque spec. Good luck!

04CompetitionOrange

I would be lead to believe its a vacuum leak as well. Disconnect & reconnect all of your vacuum lines...maybe there is just one that you are overlooking. Good luck!