At Idle Runs Fine, 50% throttle runs like ****

1990 Chevrolet Lumina 3.1L Euro 134000 miles. When started and idling car runs fine when you drive for short distances it still runs fine, But when you throttle into it as if to accelerate onto the freeway car bogs and while foot is on throttle it intermittently goes and bogs goes and bogs goes and bogs etc, and continues to do so until shut off and left alone for a while, its not as if its overheating because it does so even if driving a block then back. I Have checked all vaccum lines, changed fuel filter, cat was replaced 15000 miles ago, plugs and wires within 10000 miles, Fuel Filter within 20000, someone mentioned possible egr issue? THANK YOU VERY MUCH FOR YOUR TIME