I see knock even when the car is off lol.
This is a '93 LT1 with a 383.
The car sometimes rattles when I shut it off. Sound comes from the front of the intake or under the TB. Its not the lifters or rockers. Car surges at idle and sometimes stalls in a puff of fuel from the exhaust. It especially rattles if the idle drops below 700rpm. Its supposed to be 1000rpm.