1996 Toyota Celica no start celica

I have a code P1300 . I check the white wire(igt circuit) from ignitor to ecm ,no open or short.
Next i backprobe ecm terminal No 20 to ground , 0 volts
if I disconnect ignitor and backprobe terminal 20 , I have .7 volts
I tried a aftermarket ignitor same problem.
I check ignition coil ohmed bad replace with oem coil
I check power and ground at ecm .they check fine
I tried a ecm from another aftermarket same problem
check igf wires from ignitor to ecm , complete circuit
check wires from distributor to ecm ,complete circuit
pick up resistance within specs
crank sensor within specs
car runs for a few minutes then shuts down when code sets
any ideas