2009 VW Routan AKA Chrysler minivan with 3.8L v6. 113K miles
Couple weeks ago code P0303 popped up so I replaced the plugs and wires. I used the Champion double platinum that came stock on this engine. The light went away and we've been driving it with no issues.

This morning my wife says it did a "rough start" and it popped the same code again with the light on. Van is running great otherwise.

What else can I check?

Thanks.