[KingLT1]

These engines hold 10 quarts of oil, so being down a quart wouldn't cause an issue.

Flashing CEL is a misfire as mentioned above.

I would check the plug wires again. MSD wires are notorious for being difficult to "click" into place.

That being said with a flex sensor I wouldn't go out and floor it right away after getting fuel. If the alcohol composition changed it needs 5-10 minutes of drive time to adjust the fuel trims.