engine codes rough idle

[Scott Dog]

I just bought a 96 Cutlass Supreme CL for $500. I should have known I would have problems with it when I got home and opened the trunk and found two gallons of antifreeze, and a bottle of transmission fix. Here are the problems. I have the security light flashing, and it won't start sometimes. I did the key on for 15 minutes, then off one, the 15 etc. to get the computer to relearn. I can get it to start now, but the security light still flashes, and I sometimes have to wait about 20 seconds before it will start. I also have the service engine soon light flashing. Took the car to autozone, and the codes it read were P1870 transmission code, code 1652 Open circuit, but the fan is wired to run all the time, so I think that is the reason for that code, also a misfire in cylinder 5 code. The car runs, but has a miss in it. I'm hoping it is just a coil pack, plug wire, or plug for that code. Any information as to what to check would be great.

[Scott Dog]

Thanks for all the help!! I figured it out on my own, replaced a coil pack, all the plugs, and wires. Runs great now. Also , be sure when you change the plugs that you use platnium plugs, which are oem. Whoever changed the plugs last used cheapo autolite $1.39 plugs. I went with platnium which were not much more at 3.99 each. Also plan on spending about 3 hours changing the back plugs, unless you have little girl hands, and take plugs out without seeing them.