My 1999 SR5 Toyota 4Runner with 83k miles has a popping noise on the right hand passenger side. The vehicle will start uo with no problem and run ok, then when I shut off the truck and turn it on again 30 minutes later, with a cold engine and start driving I hit the gas and the vehicle slows down, hit the gas pedal and you hear a popping noise and the truck slows down. After pumping the gas and the truck jerking back and forth and popping noise the truck goes back to normal and gaines speed again. please help !!!!!!!