I assume you’re practicing the combos from both sides as well?
If you can do stuff consistently in training mode but can’t in match, you might just have a case of the jitters. This will improve naturally as you get used to playing people. I remember back in the day, I used to get an adrenaline rush and increased heart rate when I put a coin in the machine. Are you spazzing because you’re playing a person.
If you’re to the point where you’re nailing execution 100 times in a row in training but mashing like hell in match, you just need more experience playing with people. Honestly though, if you’re still having problems dashing, that indicates to me you still aren’t comfortable with using a stick.
The matches could also be laggy as hell. Are they? If you have a ton of input lag, it will screw with your execution.