The stock EEC computer is programmed for the stock engine size. If you rebuild your engine, stroke it, or do a 351W or larger swap, the EEC needs to be reprogrammed for proper fuel delivery. Without doing this, the computer may be giving the correct amount of fuel for a 302 into the stroked 351 that you put in. If you do not recalibrate the computer, it will never learn this on its own and you will never reach the full potential of your engine combo. We can fix this.