Power No Power Power No Power

So, my car it like came alive yesterday, threw me back in my seat and put a smile on my face, and now its back to being slow. The previous owner made a disturbing statement wheni bought it last week..."Oh yeah, i put 85 in it, its a smart car it knows when it has regular, and you have to reset the ecu before it will run right on premium again" lol....and im wondering if maybe i need to reset the ecu, i have noticed that it is a lot slower then my 92. Not just lack of mods slower, but all around...Any ideas? And i got a idiot cluster light to flicker today like maybe 1 second, i just noticed outta the corner of my eye. It was a light orange color, near the Check engine light, and it doesnt come on when the key is in and the rest light up, maybe just a glitch.....

Anyways...slowness needs fixed...

Thanks