So about a 2 months ago my mustang would randomly shake when accelerating, only in first and second gear between 2000 and 3000ish rpm's. This happened randomly for about a week and then I completely went away with no problems until about a month ago and it started doing the same thing again. So I figure it was a misfire and the plugs were bad, I changed the plugs with some NGK-IX-Iridium's and the problem was still present for about another day and then it went away again until about 2 days ago but, this time the shaking was must worse and happened at all speeds. It felt like my motor was shaking it self apart so I pulled in my garage and noticed the smell of gas and started pulling the plugs as I thought the fuel was not igniting the cylinders.

I found that the rear most driver side plug has unburnt fuel on it and there was fuel inside the cylinder. At this point I thought that the coil pack on that cylinder was bad and since I bought my mustang used about 5 months ago I figure it would be a good idea to change all of them and order a set of MSD coils packs.

They came I and I replaced all of the with the new MSD ones and the problem still exists!! I checked the voltage going to that coil pack with a spark tester from Autozone and the spark was visible jumping the gap, so I put the plug it the coil pack and grounded the plug to see if there was any spark and there was!

Now I am confused as to what is wrong with my mustang. I used a code reader to see if it was throwing any codes, and it is not (although it is a "Autozone" cheap type reader. My check engine light is not on and never came on during any of this. I have a 2001 GT, it has about 86000 miles on it. Anyone have any suggestions as to what this might be. EGR valve? Vacuum leak? Timing or bad ECU? I'm stumped here!

 

It is likely that the injectors are dirty and sluggish, and/or leaking--as much raw fuel as you describe is not a usual sign of a misfire. Another possibility would be excessive fuel pressure, you can monitor that with a physical gauge or via an OBD2 data logger.

Under what load and throttle position does the shake and shudder occur?

I would also get rid of the thin wire plugs; at least until you get this sorted out. Install a set of Motorcraft AWSF-32PP (OEM), or Champion stk #7963, double platinum plugs.

Thin wire electrode plugs offer no performance advantage other than extended life, and that they lighten your wallet reducing vehicle weight.

 

The shutter occurs at all times now, even at idle.

I thought the problem might be the injectors so I did what was easiest at the time and switch the injector from that cylinder with the one next to it an the same problem exsisted in the same cylinder. So that is why I don't think its the injectors. I don't think it is excessive fuel pressure because it is a common fuel rail to that whole bank of cylinders isn't it?? So the pressure at all the injectors should be relitively the same, i would imagine.

I'm thinking about taking it to the stealership but want to avoide that if all possible.

 

It would have been helpful if you had mentioned swapping the injectors in your first post.

I would perform a compression test before bringing it to the dealer--just to rule that out...