96 GMC 1500 V6 vortec bucks at highway cruise speed

200,000 km/ 120,000 miles
Truck starts fine and idles good, maybe some slight missing until it warms up. The most noticeable problem is at cruise speed on the highway the engine bucks with slight pressure to fuel pedal. If I press down on pedal lots of power and runs great. So basically I would say it idles great with lots of power during acceleration and at a nice cruise it runs annoyingly lousy (bucks and hesitates) with no trouble codes present. New plugs wires cap rotor fuel filter last winter ran great til 1 month ago. Today was a first, truck sat for a couple days and went to start it and just rolled over no go, finally got it going seemed to have flooded itself out and still no service engine light on yet. I have been searching high and low for possibilities bought a scanner and fuel pressure tester.