If the ECU had trouble codes to report then the CEL (check engine light on the dashboard) would be on.

That assumes that the CEL light bulb itself has not burned out and its a safe assumption that it has not.

That said, we limit the search to idle problems that will not typically throw a ECU code.

By all means get your codes read by anyone with a code reader, most auto parts chain stores will do this for free, but OBDII codes are not a bible.

Seems to me you have an erratic idle problem or an intermittent idle problem.

From your original post it seems you have already read up on VX idle probs, so my suggestion is to focus on causes that do not throw ECU codes if indeed your CEL is not on.