A buddy and I had just finished putting a set of headers on my '91 F-150 and it sounds good as all hell, it was fine all yesterday. Although when I drove to school the next morning (about 25 miles) it was a lot slower than usual on the interstate but i believe that is from the O2 sensor being taken out, we are going to drill a bung into the new headers to put the sensor back but we weren't able to when we were putting the headers on. all was fine and expected but when i got off the interstate for the last 5 miles or so, every time i was accelerating from low end of second gear it was jolting hard, just like a new driver in a manual, my buddy thought it was a miss fire but it was only happening during the bottom end in second gear, I'm not sure if the O2 Sensor would fix that or i just unleashed a whole new problem.
If anyone would know what it is or could help out it would be greatly appreciated,

Thank You,
Jack