badasp5.0

My daily driver '89 Volvo 740 when it gets superhot outside or gets to near half a tank of gas or below
it will sputter around corners and start missing at speed and eventually die out and will not start for a few hours.
I have replaced both the intank and inline fuel pumps, filters, fuel pump relay and fuses but it still acts up.
When its stalled out if you disconnect the fuel line after the regulator there is no gas when you try to start it.

What have I missed?