Engine runs rough with strange sound from the back

Hello everyone. Can anyone point me in the right direction on where to look?

After driving the car, if I shut it off and then start it again after a while (while it’s still warm), I hear some kind of bubbling or gurgling noise from the rear near the fuel tank. It almost sounds like a jet engine. At the same time, the engine runs rough/misfires and the RPM drops. If I keep it alive with a little throttle, after about a minute everything returns to normal and the car runs perfectly. This doesn’t happen every time.

So far I’ve replaced the following parts with OEM/original ones:

  • Spark plugs

  • Spark plug wires

  • Fuel filter

3000gt twin turbo, 1995, 2nd gen.

Thanks