hi guys... Have a issue on my 89 chevy pickup. Today on my way to work my ecu seems to have gone into limp mode. pegged the wideband at 10 and ran very bad... managed to get to work and did a reset on the ecu and still no good... happen to carry another with me so plugged that in with the same chip and still same problem... also happen to carry my pc with me so plugged in the cords and opened tunner pro to see what was up and it says it connects but not getting real data.. all error codes red... swapped between the 2 ecu's multiple times and finally it went back to normal... so scan was now working and i was watching it run and noticed that the factory test mode and diagnostic mode would enable for a moment then switch back to disabled... very weird.. I would suspect a short in the wireing harness.. any ideas???