Car losing power at higher rpm

[JJ Money]

So my car just started acting funny on me ive been driving my aveo the same for a year i usually shift at 5000rpm,
and it was always strong and felt great but now when i get to 2000-3000rpm my car kinda sputters as if its gonna die, it does it in all gears. my flashing check engine light came on tonight when i laid on the gas but went off after 10 minutes of driving, i have no idea what it is and ive been reading alot on here about it but got alot of diff ideas

spark plugs, timing belt, bad fuel, clogged throttle, bad oil, bad gas, ect ect so im kinda stuck here i dont really feel safe driving it honestly please help!

My car hit 80k and is giving me problems beyond belief!!!!!!! haha

Also its been 20k since last oil change have not changed plugs or sprakys in 30k not sure when last changed honestly