Had to swap out the IPR valve last week. My truck would die at highway speeds and then start only when the valve would cool off. I had my mechanic change it out. He told me that it would probably have air in the system now and would take about 50 miles to work it out. Well, it's been around 150 miles and still sputters on the top end. Will this work itself out sometime soon? Or is there something else I need to do.