I don't know for certain, but I know it was on the y pipe side of the throttle body. My Indy just explained it was leaking badly when pressure tested and was "folded over".

 

Hi Bruno, got your PM but felt it would be better to add to the thread

The issue doesn't appear to have progressed at all, i was hoping to get some warning lights at some point but nothing.

Symptoms: I start the car, it sounds ok on choke but when switching to warm idle it struggles, sounding a bit like some old v8, then it settles and drives ok but a bit sluggish, once warm she is 99% ok, the only thing I notice is if I rev at a standstill it sometimes falls below what you'd expect but never stalls

I'm leaning towards an exhaust/air leak somewhere or old coilpacks. I've logged the car on the durametric and I am seeing misfires, more so in one or two cylinders but this goes once warm. Planning on delving in and doing a big refresh at some point when I get a chance: coils, sparks, compression test, IC piping, F pipe, exhaust etc...if this doesn't fix it I will get a smoke test carried out. Will update the thread when I find out more

 

Were you ever able to figure out the issue?