Engine noise after warm up

My Sonoma truck has a ticking sound after it warms up. It sounds like a lifter sticking, but as I was replacing the valves I checked the lifters and all seemed o.k. . Some say it is an exhaust leak, but I replaced the intake and exhaust gaskets during the valve job, and the donut gasket does not appear to leak. Don't lifters normally stop ticking after the engine warms up?

Try running injector cleaner and useing a higher grade of gas. I have a 97 Sonoma with a 4.3. The injectors in the engines can tick. If the ticking speeds up as you throttle down, it may be them. Our truck always runs better on HESS gasoline octaine 89 or higher.