Welcome . As you suspected, it could be water getting into the conectors for the MLPS or VSS. I would suggest removing those connectors and drying it out first (use hairdryer). Then reset the PCM (pull Fuse 4 and 11 for a few minutes). If the OD off light flashes again or CEL codes lights up after that, scan it and you should be more aware of what the issue is. Good luck.

"Always do the cheap and easy ones first." 1996 V6 ATX 96K miles