cfr865

What would make my car sputter, cough , miss what ever you want to call it went you floor it at 60 mph when it drops down into the lower gear, it does this briefly then takes off without a miss all the the way to redline.

lawrencecar1

dirty maf ?

moosestang

dirty or malfunctioning throttle body. Assuming you have a stock throttle body.

DTMR

could be a little misfire from a bad plug or coil

Lem-06

When you were at 60. Had you been cruising at 60 for a while or only a short time.
Stayin at highway/interstate speeds causes a bubble to form in the gas pump. And pushing like that sucks it in. Sputters then back to normal

cfr865

I had been driving at low speeds and some extra idleing time, I took it back out and run the crap out of it and it seemed to quit. I see how it acts this week-end.

moosestang

Looking at your mods, it could be any number of things. I'd check the spark plugs, how many miles on them?

High flow cats could have partially melted. It's not uncommon apparently.

Nuke

Lem-06 is referring to the TSB for the fuel pump issue; I had it on the wife's '06 V6. Extended steady state cruising followed by hard acceleration and she'll buck, sputter, hesitate, etc..

Campo 427R

All good suggestions as referenced above.
I would check the fuel filter as a precaution too.
Good luck.