HELP! 97 Mustang GT 2V 4.6 Dies in Gear

Hey guys help me out. I am usually in the 95 tech area but this one is for my brother. 97 Mustang GT 4.6 2v. I disconnected his battery to re-wire a lightbar and reconnected the battery and now the car starts up idles okay, but smokes and when I put the car in Drive or Reverse it dies. I thought that once you disconnect the battery you have to reset the computer by letting it idle. But for how long I don't know. I don't know the procedure for re-connecting the battery and resetting the car so that it can run again. Any help would be greatly appreciated. The car ran fine before I disconnected the battery. What do you guys think?
 
The reason why your brother's 97 GT is dying/stalling because the 96-97's do not have the re-flashed software that comes on the newer GT's for example 99-04's. The only thing you can do is that when the car is bone cold, start it, and drive it for about 20-30mins. The computer is going to have to learn how to Idle under load in a gear and without it in gear. People, who have these year cars no what Im talking about. Its not uncommon about what your brother's problem is because it happened to me and my friend also. We both have 96 GT's.

Basically, its a very irritating/annoying but as soon as the computer learns, it will be fine. The sense able thing is to let it idle but as soon as the car is warmed up it wont be able to hold its rpm's when you put it in gear. So like I said, when the car is bone cold, start and drive for a good 20-30mins. If you have anymore questions PM me.