My 1996 Suburban 5.7L Vortec pings between 1500-2500 RPM when the engine is loaded. Sometimes outside that range. Here's an example of what it sounds like:
YouTube
I've had some pinging since I bought it in 2013, but it has started getting worse. Running some fuel system cleaner through helped. I did a tune-up in 2013 (50,000 miles ago, cap, rotor, wires, spark plugs). Fuel filter was replaced in 2015 along with fuel pump.
Due to unrelated stuff, I've had to change the rear O2 sensors, replace the exhaust flange gasket (near muffler), and now I think I have an exhaust leak at the manifold. I'm working through these problems since leaking exhaust will throw off fueling.
Beyond the exhaust/O2 system, what could be throwing off fueling and causing the pinging? Is it time to replace the injector assembly? Timing off? Tune up?