what codes did you retrieve?
What grounds did you check?
the ecm grounds the inj internally and that ground is passed to an external ground......
the ecm ground is by the ecm and by the battery under the solenoid..
if the one under the solenoid is intermit....you can have what you describe.
how are you check grounds? to properly check a ground you do a voltage drop test of the ground on a fully loaded circuit.....less than 100mv is good.
89 GT gr-40, KB2200(10psi), tweecer R/T,LC-1, 22gal cell, w/tailpipes.