Two questions about a Dodge Dakota

From : daniel j stern

Q: on fri 11 jun 2004 bob paulin wrote ive got two questions about a 91 dodge dakota 3.9 v6. the first regards a pinging light rattling sound from engine which appears if i suddenly let off the gas pedal like when switching gears for instance. it doesnt ping on acceleration i should add. a ping such as you describe might be caused by a non-functioning exhaust gas recirculation egr valve. nope. improper egr function can cause pinging under moderate acceleration and under steady-throttle cruise but not under trailing-throttle or closed-throttle conditions. -stern .