Welcome aboard mate, I think you hit it on the head yourself, repetition is the way to get things right. Coming from MMA your style of throwing is going to be slightly different. If you look at good striker in MMA some of them seem do have that stomp you mentioned. I think it's from them jabbing and trying to then get their feet set to avoid a takedown, but that's just my observation and opinion.

just find a trainer or someone at your gym that can work on smoothing it out for you and throw a million jabs and you should go OK.