when i accelerate on the gas it make's a Popping noise from engine i believe. on 1991 Plymouth Acclaim

when i drive the car at some point there's a noise which sounds like a loud pop.but as i drive with my foot on the gas at the safe rate of speed it's OK. if i let off the gas. and retreat to accelerate on the gas it make's a pop noise. what would you think is wrong with this car. could it be the timing belt or the bad vale. thank you for reading this.

Asked by for the 1991 Plymouth Acclaim
sounds like a bad valve or a camshaft problem