Smoking, bad acceleration, how to pull codes

Occasionally, my '95 with 3.2 runs like crap out of the blue. It's done it 3 times in a year before last weekend. All of a sudden I don't have any acceleration unless I barely feather the pedal, and the little I get isn't good. The "check engine" light comes on. I can put it in neutral and rev it up after which it spits out a cloud of black smoke so thick I can't see the road behind me. Then the check engine light goes out, but it doesn't run any better. In fact, driving it with the check engine light ON helps considerably. Maybe it's kicking out of closed loop? I've always limped it home, got up bright and early with my multimeter in hand, and had absolutely no problem. For Memorial Day, we drove it about 300 miles, the first time I've done a road trip with it. After 150 miles, it started doing it's thing. Never went away, and fuel mileage was about half normal. I stopped for gas and noticed the cap didn't do it's normal whoosh when i took it off. Thought maybe a stupid gas cap was my problem all along, although it seemed farfetched, so I bought one. I also cleaned the MAF sensor since I'd been convinced that was the most likely cause. Neither improved it. Got where we were going, woke up the next day, and no problem. Drove it several short trips (under 50 miles), no problems. Headed back home and it kicked in after less than 200 miles. Since the cap didn't fix it and the tank still wasn't under pressure, I thought maybe something was going on at the charcoal canister. Took the line apart at a green and white check valve? filter? in the tank line. Blew in it, sucked air through it, didn't know what was supposed to happen, so I put it back together. Got stuck in traffic and weather and didn't make it home 'til 9:30. Woke up the next day, no problem.
SOOOOOO....
It's obviously a major overfueling problem, whether in open or closed loop.
It doesn't seem to be the MAF sensor.
It's probably not the fuel cap.
It seems like something an Isuzu tech would know off the top of their head. Any here?
How do I pull codes? Is it jumper wire and dash lights? Where? I know there's an ECM under the passenger's seat.
Any other bright ideas?
Thanks for any help,
Steve.

autozone will pull codes for free.

I'd really have that checked by a pro. No offense but it doesn't seem like something you could fix. Also when you do get it fixed I recommend using one of those fuel injector cleaners that use to treat the gas. It might seem insignificant, but my 95's idle time was cut in half and the engine sounded a lot smoother. Good Luck

I'd really have that checked by a pro. No offense but it doesn't seem like something you could fix.
No offense taken, but I assure you I can fix it. I may have made myself sound like a dolt in my post, but I'm really not. I'm a dealership tech for Bobcat, build 4WD's for fun, and fabricate my own parts for stuff that's no longer available. I'm the best tech in the best dealership in my region, I've just never had a need to learn about MPFI. I bought a Haynes manual today. I'll have it licked pretty soon, but like I said it seems like something that an Isuzu tech would have run in to before.
Pulled the codes (code) and got 44, O2 sensor lean condition. For anybody that needs to know, the connector was dangling around above the driver's kick panel, but not behind it. It had been marked at one time with a white label around the harness, but was unreadable. It was the only 3-wire connector in the vicinity. I'll test the O2 sensor this weekend when I have time to warm it up and mess with it.
Assuming it's NOT the O2 sensor, anybody familiar with other possible causes? I can't see an exhaust leak waiting 150 miles to show up. The plugs are new, and have looked perfect the 2 times I've changed them. Maybe a coil pack not firing at all when it gets hot? Seems like it would still foul the plugs a little before it quit...
Thanks and keep the replies a comin',
Steve.

Intermittent problems are difficult to diagnose. Because of the amount of black smoke, the first thing that comes to mind is the fuel pressure regulator. Check the vacuum hose running to it for any sign of gasoline, past or present. I know, you'd think if the diaphragm inside went bad it would leak all of the time. But, who knows how things can fail. It's an easy thing to check and all that I can think of right now.

Dale

Whoa looks like first impression on forums are no good at all. Since you say your experienced can you tell me how I can improve power in my four banger isuzu?

Good luck with the fixin