I managed to find a shop that deals with Mustangs almost exclusively and they were local. Was having the digital cluster installed and they told me there were three cylinders showing misfires. Just to be sure, I replaced all the coils including the plugs.
For me it was cumulative. Coils and plugs helped since I had 3 bad coils, but it still ran rough. crank relearn fixed a lot of that but then it ran rough cold and when I had a full tank of gas. replaced the purge control valve and that fixed the rest. Sometimes it'll run a little rough...
I ran into a misfire issue, and it drove me crazy for MONTHS. I replaced coils, injectors, EVAP control valve, plugs and found a couple issue that sorted it out. Mine needed a crank relearn and that helped with most of it. I also found that my car didn't like the amount of ethanol that was in...