I bought a truck to flip. It's a 1988 Dodge Ram .318 83,000 original miles. It runs perfect for the first 5 minutes or so until it heats up. Once it heats up it misses or sputters when you try to accelerate from the stopped position. It also sputters at times when you are at a decent speed and you accelerate. It has a burping sound to the miss. It doesn't do at idle or when revving the engine while its in park. I'm not sure if it's an exhaust blockage or what it is so I'm reaching out to those who might know. Thanks in advance for any help. It will be greatly appreciated.