I have a 91 rs tbi it is pretty much stock . It will run great when its cold no miss or anything but after it warm up and the idle drops it will start to miss. The SES light came on one time and it was code 43 but it hasn't came on since. It also runs better with the a/c on, I don't know what else to do. I have replaced every sensor on the car but it still does it. any ideas would help.