Rough Idle

I've been having a rough idle on my '96 Mustang 5 Speed V6. I got oil changed, fuel filter changed, spark plugs & wires changed and cleaned the IAC.

Now here's a question. The CEL is on. I went to autozone to have them read it, the error was P0300 (Clynider Misfire). I changed spark plugs and wires at that time.

Now here's the thing I noticed, before changing the plugs and wires, clyinder 4 if I removed the wire from the coil the engine wouldn't change at all. It would run the same as oppose to say removing the wire from clyinder 5.

But I can't remember off the top of my head how 1-3 did. But now I notice that 1-3 when removing the wire don't have really any effect on the motor and the RPMS. But removing any from 4-6 wire, you'll notice a change. I've heard something about the '96 having a dual coil? Not sure if that's right. But if 1-3 are sparking but not causing a difference could it be the coil?

http://www.autozone.com/selectedZip,97045/initialAction,partProductDetail/initialpartType,00027/initialR,APP35943/initialvehicleId,2142201/shopping/selectZip.htm

Should I buy one just in case? Could the ignition coil be bad, even though 1-3 are sparking?

Thanks,

James

Sounds to me like it could be the coil.

Sounds to me like it could be the coil.

So even though they are sparking, it could still be the coil?

They make a test light that you clip on the plug and the plug wire on the other end. Check each coil with one of these. You can see them blink.
Available at a parts store.
Use a stethoscope and listen to each injector.
Available at a parts store.
Parts cost big money try to find the problem before buying.