Hah, ya beat me to it.
Before hand, Do you have A/M X pipe from a reputable manufacturer? (i only ask this because sometimes ebay units may not install the O2 bung in the correct area, or correct depth causing a lag in response. But, considering you did not mention this happened after a modification, i will assume at this point that is not your issue.
So, > I < would suggest you double check your wiring one more time from the O2 plug to the DME. Make sure they're all good and and no excessive resistance, bad connections etc. If you have any type of aftermarket tune, i'd probably suggest you back it up, and update your DME to the latest OEM Tune/Software to rule out any bugs in the tuning. weird shit happens, i assure you.
Afterwards, You can either:
A) replace the Oxygen sensors with a new Set of OEM's one last time to verify it's not a weird fluke, install, etc.
if the issue returns, replace the DME.
B) go straight for a DME.
Wish i had better news
