need help bad!!!

If it sat for a year, it could have bad gas in it. Change out the fuel filter and then when the tank is very low (like one galon of gas left), add a couple cans of Seafoam. Believe me, that stuff works. The tank must be super low otherwise the Seafoam wont be as effective. The engine wil run crappy sort of. You'll want to let it idle at about 2000 RPM while it burns off the Seafoam. If this method is too inconvenient, the I would recommend you take it to a shop and have the injectors cleaned out.

Do you have a Check Engine light on? How old are the plug wires and plugs? Might want to look into replacing those. Since the engine has been sitting for a long while, it's going to need some maintanance done to get it running smoothly again. The Seafoam idea is just something I thought up a few years ago. The stuff works great at cleaning gunk out of the engine, and really frees up clogged injectors. Its something to try if you have a spare can of gas laying around. If not, have shop clean them out.

Does it smoke?

Ok, wait on the seafoam. It was a suggestion as I thought maybe you had bad gas in the tank. Sitting for a year without having new fuel added is a good way to stuff up the fuel pump.. and/or injectors. What were the codes you got from the scan, exactly? And now that you mentioned the coil pack, you will want to check that out. Disconnect the coil from the harness. Careful as to not break off the plastic tabs. Get an ohm meter and test the resistance of each of the coils. Set the meter to K-ohms setting. The coilpack has 3 separate coils on it. One for every 2 cylinders. Standing directly in front of your engine bay, one coil goes from front to back, NOT left to right. So, start with the first 2 cylinders on the coil, that is, the two on the coil pack on the very left side. Make sure to not mix up the wires when you put them back later. Measure the coil from the two coil sockets. The resistance should be from 9 K ohms to 15 K ohms. After measuring, plug those two back in their correct sockets and move to the next two sockets in the middle. Repeat for the middle and then the last two. If the resistance is well out of range, replace the coil pack.

Exactly how does the engine run? Does it run any different when hot....cold? Does it shake a lot or miss? Need as much info as possible.

Since only one cylinder is affected & you have changed the plugs & wires (i"d still check #6 plug to make sure it is not faulty). That just about rules out ignition problem.

You could have a sticky injector, you may get lucky the seafoam might sort that problem.

If not ignition or fuel problem, then you need to confirm cylinder compression via Compression test or leakdown test.

Aeroman.

Plugs wires and coil are good and you have checked for spark by removing the plug from the hole and set it on an engine ground to be sure there is a good solid spark across the gap? Well if your answer was yes then it is a fuel problem not spark. The wiring harness could have been chewed by mice but lets be serious for a second mice like to build nests under the intake on a mustang not chew greasy old wires. So you grab a noid light and discover there isn't any action going to the injector after you pulled a half dozen bolts on the intake to lift it about an inch with everything except the egr pipe connected to the egr valve. Hmmm precarious .... what next .. well good chance it is the computer it will command an injector to stay open or closed when it starts to burn out, be sure to check that alternator because it was probably the fault that started all the trouble when it mysteriously started to overcharge. You might want to check your ground strap between the engine and the body, the one from the battery to the starter and the pigtail from the starter wire that grounds the body as they will burn out the computer also. Having said that there is a slim chance your injector failed and what better time than now to order up a ultrasonically cleaned and flowmatched set of stock 15 pound injectors from e-bay for less than a hundred bucks. (Hope this gets ya running)