Engine knocking noise

I have a 2000 tacoma trd v6 278k miles. Few days ago engine has a loud knocking noise. Further inspection it sound like its more on the passanger side. At idle it is loud, when i play with the throttle it sometimes stops knocking... Very odd. Truck runs and drives fine, no engine light no smoke, no miss, and knocking goes away at about 35-40mph. Could this just be carbon buildup over the years? Love my truck and would hate to tear it down for a simple fix.
I do oil changes 2-3times a year. I have not replaced spark plugs in about 2years. This summer i used cheapest gas i could find vs the 93 i typicaly use. Any advice would be awesome..never had any mechanical issues since the day i got this truck in 2001

 

Can you take a video for us. Helps to hear what's going on