It had been a few months since the Posse’s last barbecue tour. So, we reminded ourselves to be conservative and not overeat at the first stop. “I’m just going to have one rib,” said tour veteran Marshall Cooper as he drove east from Dallas on I-20. His passengers laughed. “Well, if they’re good I might have four or five,” he conceded. In the end, somehow, Texas barbecue always manages to bring out the truth. For this chapter of our barbecue chronicles, we traveled 290 miles over 10 hours on a beautiful spring Saturday that was chilly when we started and…