Hey everyone.

I got an ED XR6 engine which I'm selling.

It's running mint except for one thing.

When any throttle is applied then foot lifted off the RPM will drop down to almost 0 and the engine will almost stall.

I'm pretty sure I can hear a vacuum leak on the exhaust manifold.
Could anything else be causing this?

I'm planning to sell it with this problem fixed.

Thanks.