When i start it there is a knocking sound or taping sound coming from the engine it will eventuality go away some times quickly some times not

Heater flap? Actually my 93 Chevy has been doing that for about 2 years. I can plug the flap for a short time. Then it sounds like a ticking clock sort of in glove box.-lol. Goes away after about 15 seconds? My guess-sounds like the same issue I have. Nothing to worry about. Easy fix if it really bothers you.

I’m happy to assist further over the phone at https://www.6ya.com/expert/shannon_b38635e8878032de

alot of times when you let a car sit for a while, the oil will slowly drain down into the oil pan. When you start the engine, the knocking you hear is all the metal parts flying around, waiting for the oil pump to start spraying the oil everywhere. If you start it back up, let it run for a minute and listen for the noise to quieten down, it should eventually go away. You can help prevent the dry start as you are having by using good synthetic oil, and sometimes adding in LUCAS oil treatment.

Hard to say over the internet but I will try to explain. If the noise is a distict KNOCK KNOCK and it sounds like it is coming from the bottom of the engine, then it most likely is a rod or main bearing. If it is a TAP TAP noise that sounds like it's coming from the top of the engine, then most likely a valve lifer is failing/failed.
the fact that it goes away when the car is warm, makes me lean towards a bad lifter. Normaly if a bearing is bad and knocking, the noise doesn't go away.

The KNOCK noise will be somewhat hollow sounding and the TAP TAP sound will be more solid. If the KNOCK KNOCK is solid, then a rod or main bearing has most likely failed to the point that a new/reman engine will be needed.

Sorry for this, but usually if the engine knocks on cold start then goes away shortly, it's a sign of a rod bearing. This is just one explanation but in any case it needs checked QUICKLY! This isn't a normal sound and can only lead to bad things if not fixed.

most likey a wrist pin bad or cam bearing and last a rod bearing you need a stethascope to locate it ehrn it's knocking. could even be a pully or belt tensioner.

Need more info, what kind of noise. How many miles are on your car.What engine is in your car. If the noise sounds like an engine knock, have someone take the tension off of the belt while you check to see if Harmonic balancer moves back and forth. If it does it needs to be replaced. It will sound like an engine knock when bad. When this 1st starts to go bad it is only there part of the time. If it is this, it will eventually be there all the time and get much worse.

If the sound does not go away then the engine has internal problems. Some times if someone over revs the engine it will cause knocks.If the oil is not changed regularly and the engine gets hot due to low water,racing engine then engines dont last long.
If its a deep solid knock its a crank shaft bearing.
If its a lighter knock then some times if you remove the right plug wire and the knock goes away (of course the engine will run rough due to lost cylinder) its that pistons wrist pin bearing.
At any rate your engine will need rebuilt or replaced.Or get a different car.

5.9s are notorius for upper cylinder carbon build up and as a service manager I have used B G 44K thru the fuel as a first attempt with good results. The cheaper snake oil is a total waste of time. If that does not due it try the bottle fed option. FIND a B.G. dealer on the net.If you can, borow a boroscope,dude, you are not alone so don't feel frustated OR tear down an excellent durable motor.

One of two things is happening, either the oil pump is starting to go or the lifters are sticking. A small shot of water while the engine is running into the carb will take care of it believe it or not. Use a spray bottle or just drip very small amounts.It's like steam cleaning your engine.

check oil type and u may have worm out rod bearing