2000 Buick Regal engine

my car seems to struggle every time I get up to 100 km/hour or 2000 rpm. once im at 90 km I ease off the accelerator for a second and then continue to accell gently and every thing seems fine

Also if I really accelerate fast (like really step down) the check engine light flashes for a few seconds then disappears

Someone told me it may be a gas filter but im not sure

Thanks for the help