This is on my 84' NA. It is bone stock engine wise with 225,000mi. Just about every single day for the past couple weeks when the car is not quite warmed up yet (coolant temp gauge just about to 1st mark) I will be driving along and the car will fall on it's face, then blow a bunch of black smoke out the tail pipe.
Depending on the rpm's of when this happens (highway or city driving) determines the spectacle of this. For instance last night I was driving home on the highway (same coolant temp as above) and the car fell on it's face again...I let off the gas, and I look in the side mirror and I see the back of the car light up in a firey display followed by a cloud of black smoke. Oh with a huge pop as the fire shot out. After that the car runs great again.
My turbo shoots flames...however his car is not suppose to.

Any ideas??....I pulled the spark plugs and they look beautiful...no deposits and a nice tan color.

 

Also, I checked my AFM with my volt meter and the only check that was not up to par was the input voltage (I was reading 80mV) and the spec is 150-250mV.
Everything else was in spec AFM wise. I did re-track the wiper arm in the AFM ~ 50,000miles ago.
I was thinking timing, but the car would run poor all the time if my T-belt magically jumped a tooth.
I did replace the FPR too.

 

Must be an electrical problem. Sounds like the ignition system quits, then starts up again, and all the unburnt fuel is ignited.

Check your grounds, DME relay etc. Intermittent problems are hardest to diagnose.

 

I have the car grounded in a couple different supplemental places other than stock. Oh I did forget to mention the car has a Jacobs Omni Magnum coil so I will check the connections where it hooks up to the car original wirnig for the coil. Thanks for the reply.