Lately I've noticed an issue with my rig when it shifts into 3rd. (Auto trans)

Truck runs great, no CEL all tuned up recent maint.. blah blah blah.

Driving... 1st gear great, 2nd gear great, 3rd gear starts ok then when I get right around 2500 rpm I seem to have 'no more power' I can continue at my speed but it doesn't seem to want to continue accelerating anymore. Almost like i'm all of a sudden pulling a huge trailer and she just can't go any faster. It's not revving higher like it's slipping it just seems like it can't go any faster. Eventually it will accelerate but it's not normal. And if I give it more gas it just kinda does nothing, when I finally give it enough it will kick down to 2nd and go like a bat out of hell.

Any ideas?

 

How new are the plugs/wires? Mine had hesitation and some new easy stuff ( EO Denso plugs and NGK wires) cured it, although mines a manual. I've also heard that clogged catalytic converters can impact that as well.

Does it happen whether you run on low or high octane fuel?

I'd say start simple and go from there.

 

Not sure about the wires but the plugs have maybe 10,000 on them. I'm thinking it's more transmission related especially since it's only in 3rd gear. It runs great in all other gears.