Hello everyone! I was hoping someone could help me out with diagnosing a problem that I have on my Ford Ranger 2002 3.0L truck.

Sometimes when I start up my truck I get this really loud ticking noise coming from the left part of the engine(looking at it from the front), it gets really loud on idle and then I drive for a bit and it goes away but it is not consistent sometimes it takes longer to go away sometimes it doesn't, sometimes it ticks other times it doesn't. Here's a video I recorded of it:
I already changed the belt, pcv valve, oil and oil filter, transmission oil and filter, fuel filter. It has been happening for a good while now and I wanted to know if anybody knows what the problem is and if it's serious or not. I already checked the forums and I read that some people said that it might be a vacuum leak, if so how would I go about fixing that, also spark plugs but I haven't had time to change them out.

So any help would be greatly appreciated thank you so much!!