2012 5.4 3 valve 99k fully serviced, sound like Model T when under power

2012 5.4.3 valve, 99k miles. Fully Ford tech serviced. Timing kit, plugs, head gasket , hoses belts, bearings, steering rack etc at 55k. Heater hoses, fluids etc at 99k. No codes or drivability issues.

A sound like a Model T accelerating (puckita puckita) intermitantly happens after its warmed up. Only while my foot is on the gas pedal or when the cruise control is doing same. Lift foot off pedal and sound goes away. More noticeable on road driving or when concrete is close by to echo the sound. In general it often makes me think I'm being passed by a diesel truck.

Only obtuse thing is this vehicle has never dripped condensate from the AC drain. AC always works great front and rear. I am gonna get the drain looked at but there is no gurgle or mildew smell.

I am gonna take this to my Ford mechanic that is the only person I let work on this truck. Besides me changing the oil and air filter.

Ideas?

Dude. You have no idea how identical to my issue this is. It's been driving me nuts for a while now. Ive got a 13 with 97k miles on it. I had asked for my shop to listen for the sound and check it out before, but they couldn't hear it. For me, its after the engine is warmed up, and the engine is under load. I notice it most when going slightly up hill for some reason. But when i am passing a close building or wall you can really hear it. I tried explaining it to my wife that it sounds like an old timey black and white movie when a car engine putters out when you see it breaking down and steam coming out of it, like a puttering metal noise. Please let me know if you get any feed back on this!

If your not having a driveability or power issue, I'd be leaning towards exhaust leaks, prob at manifolds. Worse when cold and when engine is under load. Something to check anyhow.