I have a 99 GA SE V6. The guy we bought it from was having issues with it, so we got it cheap. He had taken it to several mechanics, and spent almost $2000 trying to fix it. When he had it, it would sometimes stall out while going down the road, and he wouldn't be able to start it for at least 10 minutes. Our first thought was the fuel pump, which we replaced. We didn't have a problem with it for about 6 weeks. Then it died when my BF was coming home from work. We had noticed when we changed the fuel pump that the plastic clips on the fuel lines did not seem to seal very well, and when he got out of the car that night, he could smell gas around the back of the car. Reached under and snapped the clips together, and the car started right up and drove home. When we got home, the car was pouring gas out of those clips. We cut them out and replaced them with rubber gas line. Ran good for a few more days. Now, when you try to start it, it runs like s**t, spits and sputters, pops and backfires out the exhaust, and stalls out. You can keep it running if you keep giving it gas and rev it up, but the tach bounces up and down and it will die out if you let off the gas. If you can keep it running long enough for it to warm up some, it runs fine and will start right up if you shut it off. But if it cools down, same thing all over again.
Now, here's what has been done so far:
Mechanics that looked at it before we got it have run code tests and got different things each time
Crank sensor, ignition module, fuel filter, fuel pump, O2 sensor (I think), starter, plugs and wires, and one coil pack have all been replaced (there may be more that I can't think of right now).
Last code test we ran said cylinder 4 misfire, which is why we replaced the coil pack. We then discovered that the plug wires were not right on the coil packs, fixed that but no improvement.
We were also told to try unplugging the MAF sensor, and if it stayed the same, then that was the problem. We tried that, and it got worse while it was unplugged.
If anyone has any ideas, it would be greatly appreciated. I'm ready to torch the stupid thing, lol!!!!

These GA's hav trouble with Misfires. In most cases the fuel injectors are dirty / plugd or they just arnt working properly. Most likly if you were to remove the #4 injector(or which ever one misfird) its bad.

And if this mechanic cant narrow it down, I'd take it to some one who can, with out loosing an arm & a leg.

One other thing, after a misfire, the engine will run like crap untill the code is cleared with a scanner or the problem goes away.

Hopefully you got the gas leak fixed. The issue here is that the fuel lines may be collapsing or bulging due to the pressure caused by the high pressure fuel pump. I would replace teh lines with steel or an OEM line, expensive but may eliminate part of the issue. The other issue is the PCM or engine computer. The problems you are having appear to be related to the computer and if you replace it you may find that the majority of the issues will go away. It is about the only thing left to replace!! Don't buy a new one get one from a wrecking yard so you don't have a lot of money in it. Make sure that the computer is the one for your engine and transmission combination. If you can't find one locally try car-part.com to locate one in a wrecking yard in your state.

Thank you so much for your help!!! I will try these things. Sorry it took me so long to reply, my power was out for a couple days. One other thing I forgot to mention is that 3 of the plugs were loose when we got in there also. That could be part of what caused the misfire. My friend's dad is a master mechanic, he's going to come down tomorrow and put the scanner on it. Maybe clearing the codes will help. Thanks again!!!