dan b

...knocking. Doesn't do it in idle... It almost sounds like it could just be the tires or something, except that when I tap the throttle it seems to have an effect. However, I can rev. it up in neutral all day without any kind of noise. Any ideas?

Bob W

You probably have piston or rod slap or even cam slap. Your engine is worn and tolerances have expanded to your parts in the engintekinda tap against each other.