I would be looking to a heat stressed sensor or connection.. Test time..
What you describe is dies when attains "CLOSED LOOP", prior to this happening the ECU uses a matrix, and ignores most sensors..
92 Ford Explorer, 450k
97 Ford Explorer, 400k
99 Tracker, 4dr, 4x4, 2L DOHC, auto 215k
Last edited by aquanaut20; 01-11-2017 at 08:38 AM.