1982 Toyota Pickup

I have a 22r engine. The truck sometimes won’t idle, and will sometimes cut out when I am maintaining speed at low RPM, 2000 or so, the engine will jerks as it cuts in and out. I watched it idle for a bit, and notice that fuel just trickles into the filter, and the fuel that comes out and goes to the carb has bubbles in it. Why the low flow?