Grr, my truck is surging just before the shift point and I can't seem to figure it out. Replaced nearly new fuel filter, oem fuel pump with a better one and a new air intake filter and she still does it! She's a 1997 Chev C1500 5spd V6.
Oh well, hopefully this winter's LS swap will get rid of the gremlin. Just as well I'm out of town for work until after Christmas..
I had a 96 Sierra 1500 vortec - while I didnt have that issue, try the nsmb cure from Canadian Tire - Lucas Oil Fuel System Cleaner. There's two different sized bottles available at Cdn tire, both do the same thing. I dont want to say it's a sticky injector but I doubt it's shitty gas. But on that note, Esso and Petro Can fuel have usually made my blocks have some knock/ping. Chev/Shell, not so much. Sierra included in that.
Also, if you use the fuel system cleaner, take it for a run on the highway with the heat/vents off and run it out. I passed air care in my Sierra that way by hitting a highway loop and not using 5th all that often.
protect tom mcdonald at all costs