I got a problem

[98RedRanger]

Ok when I'm cruising down the road at about 55 or so in 5th gear my truck starts lurching almost like it's missing but I don't hear a miss and I just replaced the spark plugs by the book maybe 4 months ago. I can normally figure out what it is and fix it but this ones got me stumped. It doesn't do it in lower gears and it gets bad over 60. Any ideas?

 

[Ranger Dave (B25)]

Fuel pressure not keeping up, clogged fuel filter, boogered up sensor(s) of some variety, could be several things.