CouldHelp/exhaust leak cause erratic idle/stalling?

[jester911]

I did a search and came up with nothing conclusive.
I just last week changed my exhaust to a 1 in 2 out muffler and europremuffler. Stock heat exchangers.

Car ran perfectly before change. Now it has erratic idle and when going from dead start in 1st it will sometimes try to stall.

I can't seem to detect any leaks but doing a search I came up with symptoms similar with a vacuum leak.

Will an exhaust leak act the same way as a vacuum?

I did no other mods at all before so it seems it must be the exhaust.

Also for reference I have had a cat bypass on my car for the last 4 years before I went to premuffler.
It had an O2 sensor in the bung but has never been plugged in. I set up the premuffler the same way.

[jester911]

bump

[jester911]

Okay guys,

I know it is a little slow today but ....
Anyone...Bueller

[jester911]

...

[azasadny]

Did you knock a vacuum hose loose?

[jester911]

Unless there are vacuum lines under the car, no. I never opened the engine lid. Everything was underneath.