Man oh man. Just when I get thing running great another problem pops up. My truck will surge, tack will move back and forth when I'm traveling up to 40 MPH. Tack will move around 200-300rpm's. After 40 theres no surging at all. Checked for vacuum leaks, carb seems to be OK as far as float,choke,etc. Timing is right on at 35 degrees total. Any suggestions?