Ok I have a 2002 gt mustang with 50000 miles on it the service engine soon light came on and I checked it out and had cylinder misfires so I swaped the spark plugs out for some bosch platnium +4, Then it still came on and had random cylinder misfires etc... So I checked the alternator and it came up bad so I thought since the battery wasnt being charged that it confused the ecu. So I charged the batt, and then put a new alternator in the car, And damn it it still keeps coming on so I put 8 new msd coil packs on the car, But still keeps coming on. The guy at advance auto thinks that bosch doesnt work well with ford and thinks that the plugs could be my problem. What do you think? I need help I am at a loss.

 

Get rid of the silly +4 plugs and install a set of Motorcraft or Champion platinum plugs. The additional electrodes will often disturb the air/fuel mix's flow around the spark plug tip and even reduce performance and cause misfires.

Other than some specialty applications, multiple side-electrode plugs are at best an attempt to extend plug life, however they are mostly a marketing gimmick.

If that fixes the misfires then re-install the OEM COPs, they can provide plenty of spark for any but the most radical builds, and will last longer than most after market COPs--most of which are mode by an OEM supplier named Micro-Tech.