No power at cruising speed

Hi guys, I have a 1993 GTO and looking for an opinion. When cruising at say 65 mph, if I put the foot down to overtake, there is little or no response. She slowly gains speed.
Could this be the Mass flow meter or the O2 sensor on the exhaust ? Or something else. Suggestions please so I could try to narrow down the problem.

I should mention that it’s a non turbo

Is it at high-speed or just generally it’s being slugish?

Hey cableguy, just at high speed otherwise she’s fine starting off and driving.

May want to look at Throttle Position Sensor on throttle body… take a obdii reader and see what %'s you are getting when accelerating. when fully pressed you should get around 94-95%. In theory, i suspect you could get 100% wide open but i have not experience that myself. if you do replace or loosen bolts, if set incorrectly can cause the car to buck harshly, so it does matter how it is adjusted. After that then maybe the MAF.

Thanks royboy25, I’ll look at that too. I’ve discovered a crack in the exhaust manifold which won’t help either. I’ve alot of work to do.