I've done alot of ford fuel pumps before and never had that problem before. Disconnecting the battery may work, but may not either. From '96 on all vehicals are equiped with OBDII, the "soft codes" will be ereased, but any hard codes (ie misfires etc.) will probably stay in the computer. Shoerfast is right in the fact that manufactures do what ever they can to get people to bring there cars back to the dealer. I'm not saying that you won't have to take it back to the dealer, but you might. I had an 05 chevy truck, and an 04 monte carlo in the shop for regular maintenence work ( the same guy owned both vehicals), well the keys were on one ring, and they look identical. One of my techs stuck the truck key in the monte and poof, scrambled the tumbles right there. had to get in towed to the dealer. So i know what kind of a boat your in right now, good luck