Daily driven 71 now runs like crap after a 700 mile trip (and WTF is this sound?)

[BigTopGT]

Super frustrated, fellas.

I've got a 71 with a basic SBC 350/700R4 combo and I'd been daily driving it in south florida for literally 2+ years without any issues. (Hedman mid lengths, Erson 1.5 rockers, edelbrock intake manifold, Holly 650 carb, full Magnaflow exhaust, etc...)

With little more than occasional maintenance, the truck always started on the first hit of the key and idled/ran/drove like a champ the entire time.

After a long drive from Florida to central NC, the truck hasn't run right since.

Now, when I start it, it runs rough & I've got to give it a little gas until it warms up. If I don't, it'll stall any time I even put it in drive.

I'm not even sure where to START looking, since it seems so random and out of the blue.

If anyone has some advice, I can't tell you how much I appreciate it.

It's also had a knocking sound that's been nagging me for months. It comes and it goes and I thought a new crank balancer would resolve the issue, but no such luck. (it's loudest when the truck is cold and it's quiet when it's warm)

Really trying to not pull my hair out here...


Video of the noise I've been chasing

https://youtu.be/mC7LzL19K6g?si=v_HAxJV4iIsbzDkD

[Dead Parrot]

Knock sounds like exhaust leak. Those can be hard to chase. Don't overlook the intake exhaust crossover. Yes, a bad intake gasket can cause an exhaust leak.

Take all the belts off and give it a short run. Possible the 'knock' is one of the accessories being EOL. If things get quiet with no belts, go through the process of elimination until you find the noisy accessory. May also be easier to track down the leak or internal noise without the fan and other noises. Just don't get lost in noise tracking that you forget the short run part.

Rough running could be a simple as it needs a tune up.