Clicking or tappting upon starting

Sounds like you have bad lifters until they pump up with oil they make noise they click or tap loudly until they fill up with oil

Model year ?

Leaking intake manifold (vacuum )

sounds like a bad coil check and replace

this does sound like theres a loose line tapping the engine/frame,during warm up the engine idles faster which could make it vibrate faster causing the the clanking or tapping noise,if this has started after trans fluid change,then check the lines running from the trani to radiator sometimes the service person might bang into something causing plastic clips that hold the lines to break,try getting under it and have someone start the truck and listen to see where it's coming from also hold the lines & see if the noise stops,the service guy could have unbolted something & never put the bolt back causing the clank ex.line may have a clip holding it thats bolted to the trani pan ?good luck

Sounds like a hydraulic lifter that looses its prime while not running.

A hydraulic valve lifter transfers the rotating motion of the camshaft to the valve train, causing valves to open and close as dictated by crankshaft and ignition requirements. It operates on a cushion of oil in its bore.

It's not uncommon for this to happen, especially if this is what one might consider a "high mileage" engine. Since you've indicated it quietens down after it warms up, it shouldn't be considered a serious problem. Regularly scheduled oil and filter changes, using a good multi viscosity oil and a good oil filter can do wonders to prolong the effective life of your engine. I run Pennzoil 10w30 and Fram filters....but there are many good brands out there.

You might want to consider a good quality oil additive....it might improve the situation.

Personally, I'm partial to Lucas Oil products. These are available in most auto parts stores, and I've also seen it in WalMart (usually a little cheaper).

In any event....good luck!

Start with a tune up, spark plugs, spark plug wires, fuel filter, air filter and that might cure the PO300B code, hope this helps, Gary

DTC Number
P0160 DTC Name O2 Sensor Circuit No Activity Detected Bank 2 Sensor DTC Number P0300 DTC Name Random/Multiple Cylinder Misfire Detected

Nope. This is an Exhaust Leak. You need to replace the Exhaust Manifold Gaskets.

THIS IS NORMAL noise for your truck. carbon buildup on pistons causes a cold start knock until warms up. you can run some top engine cleaner thru engine to help. but noise is nothing to affect life of engine