sounds like it could be the timing when it's under a load.
A 1993 Ford Aerostar would have come from the factory with ( 5W-30 )
That would be 21 gallons.
it is out of time or the plug wires are connected incorrectly.
would have driven
If it backfires while you are driving, the intake manifold bolts may be loose or the gasket may need to be replaced. If it backfires when you turn off the ignition, the fuel mixture is a little on the rich side.
Could be many possibilities. It would depend on year and model of vehicle you have.
It has either . jumped timing
the radiotor or the cams
1992 lt1 corvette runs good until it reaches 190 degrees the starts rough idel and backfires/ the car would kinda run rich in its past with black smoke at times
Check the fuses
Your timing is way off, it needs to be reset
A Ford Aerostar would have come from the factory with a 50 / 50 mix of distilled water and GREEN color antifreeze ( meeting Ford specification ESE-M97B44-A )