2-3 times so far (bought jeep 2 weeks ago) when I took off from in front of the house normally, I got a backfire through the intake. I am going to check for vacuum leaks tomorrow, but does anybody have any other ideas? 144k mi, head was redone last year, plugs, cap wires in feb, 4cyl auto. Runs slightly rough when you start it, 10-15 seconds later it smooths out. Thanks!