Car miss firing under load

[bobcat]

Hey folks, I have a 96 mustang Cobra that has a mis fire under acceleration. Doesn't seem to happen all the time but more often than not. I bought the car several years ago as a project. At the time I it had several issues many of those have been addressed. one that is still haunting me is this nagging misfire. I have replaced plugs, wires and coil packs. Fuel filter. I will add that for some reason the car will drain the battery if I keep it hooked up. Don't know why it does this or if that could be related to my misfire issue. As you guys know there isn't really anything that should draw power while the car is off. One thing I've read is the amps for the factory Mach 460 system have been known to quit "going to sleep" when the key is off. Can't seem to find a fuse dedicated for these amps to remove. But any way not even sure that is causing my misfire. One issue at a time . I would really like to fix the misfire first. The car is a blast to drive but would be even better without the misfire. If anyone can point me in a direction I would greatly appreciate it. I do my best to do as much of my own repairs myself. I'm an old school diy mechanic and I can do most anything to old school cars but sometimes I get stuck

 

[cobrajeff96]

More than likely there is a bad coil pack or a bad plug or wire or some combination of them. You can easily test for them...

First, trip the fuel safety inertia switch in the trunk to disable the fuel pump in order to keep the engine from flooding. Pull one plug at a time, leaving it fully connected to the ignition system. Ground the plug's ground strap to some bare metal, maybe the top of the strut assembly while someone cranks the key. You should see a very strong spark. Just repeat it for all 8 cylinders.