If anyone has thoughts or previous experience with this sort of workflow (or a better way to do it). I'd greatly appreciate any feedback/help.
If the fields are already in Marketo, you may have to ask Support to help with the mapping.
Yes they're already in Salesforce. I'm primarily working with the Lead Source field. I just realized I was trying to use a custom field in a Marketo form instead of the Lead Source field already there. I'll test it out with that and respond back with my findings.
Quick followup: Any thoughts on why my Lead Status is changing to 'Not in Program' even though I have a flow step to set the data value to 'Open'? In Salesforce, I'm getting an update that the lead owner changes the status from 'Open' to 'Not in Program' the moment the lead is created, so I think I've got something in my Marketo flow or Salesforce settings that is overriding that flow step.
Again, I appreciate all your help.
Also, side note, did a quick search for UTM trying to quickly get to my post. Realized my original question has be asked several times before. That said, I appreciate the helpful responses!