Luffy ran, Doflamingo at no point never ran from Luffy.
Luffy can't even finished Gamma Knifed Doflamingo after using G4, and he started to run from him. Read the manga, don't look at the conclusion with Zoro fan goggles.
I guess has no concept on how a human body works...
Whitebeard gave a free shot to Admiral Akainu because he had
a heart attack.
Gamma Knife destroys internal organs including the heart.
Doflamingo was trying to survive by stitching his heart and other internal organs back.
Even Whitebeard didn't stop when 1/3 of his face melted by magma, but he stopped when he got an heart attack.
Seriously, even though you are always trolling Extralad, you should also think on it a little.
No, Luffy couldn't finish him in time, then he started to run. Stop making up funny excuses like you always do.
Doflamingo never got blitzed if he wasn't Gamma Knifed and caught by surprise. Once he used Awakening, Luffy lost his advantage.