[SpaceCatsAZ]

Idle is a bit high, at 1000 rpm. Engine is also "moosing" (from the faq) Could a exhaust leak at the manifold flange cause the idle increase? All intake gaskets are new,

 

[mmc757]

Moosing is normally the IACV.

Not sure how an exhaust leak would cause that...do you have a known exhaust leak?

 

[SpaceCatsAZ]

Moosing is normally the IACV.

Not sure how an exhaust leak would cause that...do you have a known exhaust leak?

Yep. Have a broken rear manifold stud that's mostly fixed, but still a bit bodged. As you know the secondary O2 sensor is on the y-pipe. I know its not usual but ive seen an O2 getting bad info and effect idle on a few engines in my time. I had partial moosing months ago and google said it was the DPFS or EGR so I replaced both and it went away until now. The IAC is new from a previous owner and pretty clean so I was just wondering.