sticky needle syndrome isn't uncommon on a carb that has sat with gas in it for a while. Could also have a leaky float that isn't floating so well any more. It should clear up pretty quick once you get some fresh gas going through it. You can also clean things up a lot just pulling the gas inlet off at the carb, cleaning the screen and the seat. There is a bolt that goes through the inlet (follow the fuel line into the carb, you'll see it) with a metal clip. Bend back the clip, unbolt, and gently lift off the whole works being careful of the screen inside.
The weber upgrade is great, but I think I liked it more for how simple it made everything under the hood than anything it did for power. I took mine off when I was doing a lot of highway driving because I got tired of listening to it suck air all the time. Next time it goes back on I fab an air box and put the inlet out near the grill somewhere. (Or fix all the holes in my firewall, one or the other...

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