Report "1999 Dodge Ram, 5.9, automatic, 4X4. The truck starts fine and idles normal for about a minute. Then it begins to idle extremely rough for about 2 minutes and then runs fine afterwards. If I am driving when it starts running rough, it loses almost all power, hesitates and begins to backfire through the intake. The harder I push on the gas peddle the more it backfires until it is wide open and then it takes off like a rocket. I have replaced plugs, wires, cap, rotor, fuel filter and air filter. I have drained the tank and filled it with gas from 3 different stations. Also, I am only getting about 9 miles per gallon. Not sure if they are related problems though. The gas mileage issue has been going on about a year. Any suggestions?"