Weird engine light
 

When I accelerate up a hill and it goes into overdrive and stays in overdrive for like…10 seconds, my engine light starts flashing at me, and when I stop accelerating the light shuts off after 10 seconds.. Any ideas??

A flashing SES light signals a serious misfire situation that can potentially damage the engine. Read any codes that might be stored and/or get the problem looked at. BTW, what are you driving?

Its a 2001 LS 2Dr. 4X4... But if the light shuts off after im done accelerating there is no codes. Right?

Codes could still be stored.

I went to advanced auto today and checked the codes, and there wasn't any codes stored.. since its a misfire can it be fixed with a simple tune-up?

That would be the way to start, but I suspect that the problem may come back. There are factors that can cause misfires beyond what a simple tune-up addresses.