Toyota pickups have a reputation as being nearly indestructible. While it's true they go thousands of miles with little or no attention, they do have their quirks. Toyota carburetors, in particular, can be a bit fussy.
Like any carburetor, the one on your Toyota truck is prone to clogged jets. An occasional spray of cleaner down the throat can help, or try a can of fuel additive every other oil change.
Pay particular attention to the vacuum lines between the carburetor and valve cover on these little trucks, where the high heat can cause them to loosen or harden and crack. Also check between the engine and fender well for lines that tend to get disconnected accidentally during an oil change or other service.
Problems with the float can cause poor throttle response and a host of other woes. Check the sight glass on the float bowl if your model has one; the fuel level should be between the marks. Otherwise, pull the top off and check the float level with a gauge. Also make sure the float isn't sticking or leaking.
Eventually, even a Toyota carburetor needs a rebuild. Make sure you get a good kit with full instructions. The kit should also contain a needle and seat valve and an accelerator pump diaphragm, two of the most trouble-prone parts.
