Try to keep things simple, and stay cool, you tend to throw out attacks and Ultras even when you’re not in range. Reduce the amount of wake up reversals, and block more. Blocking is very good.
You seem to understand that far MK is Guys furthest poke. That’s good, but again you’re not quite in range most of the time, and throw it out unnecessarily. Pokes keep opponents.away and pressured, but you should limit them to reacting upon an opponents approach, otherwise you’re simply extending your hurtbox, becoming a target for a big whiff punish.
As above people said, BnB combos are.crucial, especially anything that leads to Run slide. But I also think you need to gain a thorough understanding of Guys normals. Try all of them out at different ranges, look at their speed, combo potential, etc.
You could also watch games of long time Guy players to see their application.
Keep at it, good luck.