It sounds like the injectors were clogged up and not spraying with atomization which will cause what you were experiencing.
couple of options.#1 Take it to a shop and have them do an injector cleaning which will also clean up the valves and combustion
chamber.#2 Run your fuel tank to 1/2 or a little lower and try a fuel system cleaner which i would double dose. Then drive the car
hard on the highway Putting your foot into it and look for black smoke. You could also do a top end cleaning with a cleaner of your choice.
I would recommend the in tank and top end cleaning for sure.