All lifters started clicking at once - 1998 Chevrolet C1500

This type of noise is usually caused by malfunctioning valve lifters or an exhaust manifold leak. If the noise lasts for more than a minute and completely disappears or dimishes after the engine is warm, the most likely cause is an exhaust manifold leak. If the noise only lasts for a few seconds, the most likely cause is a valve lifter malfunction. You should start your diagnosis with a visual inspection of the exhaust system. Inspect the exhaust manifolds for leaking gaskets or cracks. Black soot marks where the manifold mates to the cylinder head are key indicators of an exhaust manifold gasket leak. Inspect for broken exhaust manifold bolts. Inspect the gasket area where the manifold bolts to the exhaust pipe. Small exhaust leaks can often self seal once the metal engine parts are heated and expanded.
If there are no signs of an exhaust leak and the noise dissipates a few seconds after starting the vehicle, you should suspect an oil control or valve lifter malfunction. Hydraulic valve lifters use the engines oil pressure to expand the lifter which provides a zero valve lash clearance. This prevents the valves from tapping. When the engine is shut off, a valve and spring in the lifter keep it expanded and retain the oil within the lifter. If the valve or spring allows the oil to drain from the lifter, it will collapse. Upon start up, the lifter will take a few moments to "pump up" and expand as the oil pressure builds in the engine. During this time, the valves may tap since there is clearance between the rocker arm and lifter..

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indicates problem or worn hydraulic followers /lifters
pull them and have them tested with a leak down test
check the oil filter in use as some cheap brands do not have a nonreturn valve in them so the oil from the lifters drains back and the lifters run dry

The old fashioned way was to connect everything up and tighten the nut on the lifters until you could no longer turn the pushrod and then add about a quarter turn. Cover the lifters with a rag then start the engine with the valve cover off and loosen one lifter at a time until you hear it clicking and then tighten just until the clicking stops. Do that on all lifters ona at a time. Whe complete go back and add one quarter turn to each lifter.

The 'light tick' is most probably a valve lifter. The valve lifters in the engine are hydraulic, and are pressurized by the engine's oil pump.
When the engine gets some mileage, say 60 or 70 thousand miles or more, the engine is just not as tight as it once was. What happens is that the lifter loses its pressure when the engine is not running, because there is some wear. When you start the engine, the lifter takes a few moments to pressurize, and makers a ticking noise until it does. The 'ticking' is the sound of the valve being hit by the push rod, which is being pushed by the lifter. Once the lifter is pressurized, the 'ticking' sound stops. This is a very common thing for engines, it will eventually happen to nearly every one.
Sometimes, thin, old oil can cause this. If you have not changed the oil/filter in a while, you should do it now.

This is nothing to really worry about right now, but it is a sign of engine wear. Just be sure to run the proper oil in the engine, and do all the proper maintenance.

This is most likely a noisy lifter (or valve tappet). In cold weather, the clearances in the valve train open up because metal contracts due to the cold. Once the oil pressure comes up after start the noise goes away because the larger clearance fills with oil and the lifter becomes "cushioned" with the oil. The proper fix is to have the valves adjusted. I believe in your model, that is done by putting shims on the lifters. This will quiet the noisy lifters. In the short term, you can try using a lighter weight oil for cold weather. This will get the oil to the lifters faster after start up and quiet the tapping more quickly. Once the weather warms again, shift back to the normal weight.

try running some lucas in your engine you can find it at your local parts store if that doesnt help youll need new lifters.

Listening to you spell wrong and guess the theres a lifter tap when the engine warms up it goes away runs good all the time? Sure alot of 4.0 and some 5.2 V8 do this. Missed a few oil changes did we? Heres what happened and something that might make it go away (maybe) ( It'll be back later) The lifters have accumulated some varnish and as the engine warms the clearnce relaxes and the lifter tighten s the vavle train and the noise stopps. Most engines stop in the same place in their firing order every time you shut them off. So a certain valve is being held open by the lifter and the cam as the car sits parked. The oil slowly leakes down out of the lifter. then you start up the oil presure comes up slowly in the lifter galley and finally the lifter fille=s back up the lash is closed and it stopps clicking. Change the oil and add a can of fuel injector cleaner as the lifter will pump up quicker if it were clean you may have to change the oil very week for awile as your washing out the dirt that would have been chnges if the oil was changed enought. Cheap oil is good if you plan to change it more than once

it's simply means that the lifter empties after a while so when you start it it fills up again and the you're good to go.

it's not very dangerous for the engine but in my opinion it's better to have it replaced...

Sounds like you could use an oil change....

low oil psi need to remove pan and check oil pickup