Code P0717 and a rough idle?

[minig646]

Hey guys, my rear valve cover gasket has been leaking on my 99 SLE V6 and I decided to tackle it for the first time today, which of course meant removing the intake manifold. Everything went fine and I labeled all my hoses/wires and no nuts/bolts were left over. Then I started her up- I'm getting a noticeably different sound at idle, it idles rough, I hear a hissing sound (but can't find it) and I'm getting code p0717- SYSTEM TOO LEAN.

Obviously, there could be a million causes for this probable vacuum leak, but I'm curious if there's anything specific to check given the work I just did. I didn't touch the maf and all my hoses are back where they used to be. If anyone has some advice on what to check I'd really appreciate it!

[Gregtrd]

Make sure that the throttle body gasket is not backwards. Code should be po171

[minig646]

I checked to see if it was upside down but it's not. Could putting it on backwards really cause a vacuum leak?

[Gregtrd]

Yes, been there done that, make sure that the shape of the gasket matches
the intake inlet.

[1gSE]

Yes, been there done that, make sure that the shape of the gasket matches
the intake inlet.

oh man tell me about it! The scariest part was seeing the wide band pegged on the lean side