5.0 keeps on Cutting out

What should we do? My friends 5.0 keeps cutting out, as if it is mis firig. The car has 11:1 pop up pistons, ported c9 heads, a solid lift cam, .528, 230*. The car is an 88 fulie car with mass air conversion, 4:30's and a t5. We have tried everything. We took out the msd box, swaped in several distributors, a different coil, we chacked the ignotion switch and the neutra safety. The problem was pretty bad at first, because the car would just cut out right away. And i mean shut off. Now, it had a miss at wot, and it will randomly happen in any gear. What should we do?

I had the same problem with my 84 Merc Capri.
It's the same fox body and wiring - just under the Mercury name.
But what I found to be my culprit was in (under) the steering column.
Where the key tumbler is - there is a plastic snap-clip together component
that houses a copper slide.
when you turn the key - it moves this slide.
This slide is what makes contact to provide the main power to the console and ignition, as well as the starter.

What happens is the plastic get's hot, and as well get's old and the clips that holds
everything together breaks. In my case - I only had 1 clip holding everything together, and when I hit a bump and reving really high down the strip - the contact spread out and then opened the circuit cutting out power.

As soon as you pull the cover off the underside of the steering column, I think there was 1 screw holding everything up. Be careful, if the clip(s) are broken and it comes undone - the spring and slide will fly out.

I wound up 'rewiring' and creating a custom panel for the ignition, gauges and using only the key for the steering lock.
So - essentially, I wound up hotwiring my own car :P

This maybe from left field. But had a problem with my son in laws like that.
Unplugged the mass air sensor, made the computer go into limp mode.
Problem disappeared.