Today I resprocketed my bike and installed my flush mount signals..So I had only a little time to check a few things on the mustang..Vacuum leaks, plug wires, distributor, etc.
I sprayed the wires down with water and found no arching...The look relatively new and have no corrossion on either end..
I've seen plenty of plugged cats and exhausts.... The car doesn't bog down like a plugged exhuast system under load...I have 3" equal lenght headers with a hooker x-pipe and single chamber 3" mufflers...Very loud and unrestrictive..the mufflers are tiny..I'm actually debatting switching to flowmasters dual chamber, just to quiet it up a little...
Just going back to basics here - when I built up my 5.0 and ran it for awhile it started bucking, pausing before accelerating etc... I had two burned plug wires that would fire at idle but would arc to the headers under load. Equal length headers are hard on wires. Just make sure you don't have the same problem I did.
I don't know what kind of mufflers the car has but I had fiberglass filled mufflers back in high school that failed and pluged the exit of the muffler... car would run but not very well. If you're running rich you could melt enough fiberglass to allow it to enter the outlet...
Since you've already ruled out a compression issue, it's either fuel or ignition related. The fact that your plugs are black right away tells me you have a fuel issue - way too much of it. Get the wideband O2 sensors working and start tuning... You'll score the cylinders if you run rich for too long so be careful.
I sprayed the wires down with water and found no arching...The look relatively new and have no corrossion on either end..
I've seen plenty of plugged cats and exhausts.... The car doesn't bog down like a plugged exhuast system under load...I have 3" equal lenght headers with a hooker x-pipe and single chamber 3" mufflers...Very loud and unrestrictive..the mufflers are tiny..I'm actually debatting switching to flowmasters dual chamber, just to quiet it up a little...