"bogs" down over 55

I have a 1988 chevy 454 engine. It runs fine until I get to around 55 mph and the four barrel opens up. When I press the accelerator it sort of "bogs" down like it won't go any faster. I had carb. rebuilt, changed to
fuel pump and gas filter but it still does the same thing. Help!
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Does the truck have a catalytic converter? Might be severely restricted /almost plugged. Happened to me on an 81 Suburban. Put in a "test pipe" and voila! Problem cured.

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I had a 460 in a motorhome that had the same symptoms. Ended up being the distributor rotor and cap.

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