I have a 87 4runner with the 22re in it, the head was replaced. When at Idle you dont hear any knocking until the motor is under load(when its being driven) not too sure what it might be? The Bearings? or maybe a wrist pin The previous owner said he had the same problem with the old block so he through this one in but it is doing the same thing.

 

piston slap, wrist pin, rod berring. hard to say if it runs good run it untill it dies