Where is the Fuel / Air Mixture screw?!

So I've taken off my filter cover attempting to find this screw.. My truck will surge or buck like it's not getting enough fuel. I found the long crosspoint screw that adjusts idle speed. Could anyone help me find the mixture screw please?

I found a link for ya that may help. but i might try small easy fixes like fuel filter before tinkering around with the tuning of the carb. the link is pretty much what the chilton manual has you do when adjusting air fuel

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