I bought this car from my wifes uncle. It needed a upper intake manifold so I fixed it and put new Delco wires and plugs in and changed the oil. Car has 82000 and cleaned up very nice. Ok now for the problem. After driving for 15 minutes plus you will pull up to a stoplight and take off and it is at a big loss for power. Pull up to the next stoplight and it will run fine. Since this I have also put a new cat on. I cannot figure this thing out and it does not have any codes or ses light on. Any ideas would be greatly aprreciated. Thanks