My son has an 87 2.3 L LX.
When he drives it, it will all of a sudden lose power, sputter, stutter, and then all of a sudden the power comes back , but with a big cloud of black smoke. We tried it through Aircare 2 months ago, and I can't remember what the numbers were, but seems like it was running very rich.
Any ideas?
When does this happen? At idle, while driving, while accelerating, while braking? Since its running, the fuel pump, relay, and regulator are at least partially working.
Knee jerk point to start would be fuel pressure regulator. If you have a fuel pressure tester, you can connect it to the service port (looks like a tire pressure valve on the fuel rail between the TB and the firewall) and start the car, you should see the pressure remain steady and I think about 30 - 40 psi but I could be wrong, welcome more accurate info out there)
Another point could be fuel filter - make sure its been changed recently. if its clogged, you could be getting pressure bursts through the system which could break your injectors.
And, it could also be the fuel pump itself. ITs located in the fuel tank.
All 87 and up mustangs are fuel injected.
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1988 LX 2.3NA Cammed (@.050 duration .201/210 Lobe center angle @ 112 degrees Lift is .400/.406) 1.89/1.59 cheater valves, 30degree keepers, HD valve springs. 3" exhaust pipe intake. 5-speed MT.
1966 Notchback (in storage slowly rotting away) 289 cid factory original. Begging to be restored.
I agree with the electrical issue, however there is one fact that would direct me otherwise. The black smoke you are seeing indicates a rich fuel mix in the engine at the time the ignition fires.
You are getting spark because you are getting the smoke (the fuel charge is being burned), and although a tune up is a good idea, I would check the condition of the fuel system first. Then I would check the ignition system.
So, when you do a tune up, look for ignition wires that keep their shape and are not easily pliable. The wires wear from the inside out and basically are made like a pencil. The graphite inside the wires becomes dry and brittle and cracks which causes problems. If they tend to hold the shape of the path they are run, then they are probably old and need to be changed. Next, check the plugs. They will most likely be black and sooty indicating a rich fuel mixture. Gotta fix the rich fuel problem first or you will foul out your new ignition parts.
As for your cap and rotor, check them for corrosion on the aluminum terminals and wear on the carbon tab in the center of the cap. It will look like an ashen colored buildup ont he tabs under the opints where the plug wires connect. If you do not know how old they are, I would replace cap, rotor, plugs and wires. I recommend brass connectors (high performance quality) over aluminum in the cap, brass doesn't corrode like aluminum does. IF you are budget concious and elect an aluminum cap, spray some silicone spray inside the cap before installing. This will limit moisture buildup in the cap and help keep the cap from corroding.
As for plugs, I recommend platinum, the brand I have run for 20 years are the BOSCH Platinum PLUS. they are about $2.98 each or so at your neighborhood parts store, but worth it. You dont get the wear and gap change associated with copper core plugs. And, you get better energy in the cylinder where you need it most. For reliability, I have run them in diesel and although I had to constantly clean the oil off of them, they kept firing and got me home about 200 miles away! THAT is a story of stories! HA!
Unless you are doing performance racing, etc, I wouldn't worry about the coil if the car is running reliably at all. The coil really doesn't fail partially, but when it does, the car isn't going to start at all.
Hope this helps, and good luck.
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1988 LX 2.3NA Cammed (@.050 duration .201/210 Lobe center angle @ 112 degrees Lift is .400/.406) 1.89/1.59 cheater valves, 30degree keepers, HD valve springs. 3" exhaust pipe intake. 5-speed MT.
1966 Notchback (in storage slowly rotting away) 289 cid factory original. Begging to be restored.
again, I'll bet the problem is a bad MAP (mainfold absolute pressure) sensor, mounted back on the firewall.....same symptoms you dscribe and a very common problem on speed density cars wth EFI....
Car sputters, stutters, and then black smoke 
