Back in the day I personally knew or knew of probably 20 people that had 5.0 Mustangs. One thing I remember very clearly is that bone stock Mustang "a" could be significantly faster or slower than bone stock Mustang "b". Seemingly identical cars would often run very differently from each other.
The best that me and my non-Ford buddies could figure is that the production tolerances weren't very well handled by the factory. If you got lucky you might get a car that had a well built engine, and if you were unlucky you got the one with wild variances in the weight of the rods and pistons, and / or a crappy casting on the heads, and / or piston rings with a 1/2 inch gap, etc.
Oh, and I remember the automatics being particularly pathetic. I once drove my buddie's mom's automatic '89 Mustang convertible, and the thing wouldn't even do a brake stand. It just revved up against the converter to about 2200 rpm and sat there - no wheel spin at all.
