I recently bought an 04 Lariat Crew Cab with 56k miles auto trans and 5.4. Before I bought it I complained that it had an exhaust noise, an acceleration issue at 40 mph and 1100 rpm’s and the ac was not very cold. They replaced the exhaust manifold on pas side, the coil pack on the #3 cylinder, recharged the AC, did a tranny flush and a flash drive update. It seemed to fix the problems for the most part but I drove mostly 30 mph or less to and from work. I took it on a few road trips on the highway and country roads (40-60+ mph) and noticed the problem again and it became more consistent. It happens pretty much all the time when ac is on and overdrive is on between 40-60 mph and after decelerating and slowly accelerating. Less noticeable or less consistent with ac off and have never noticed it with over drive off under the same mentioned conditions and mph range. It feels like a limited slip kicking in or driving on dry pavement with 4wd on when it happens. The tranny shifts fine in straight acceleration pulls through all gears and even full throttle pulls. Problem only happens after decelerating and slowly accelerating. Any thoughts? Brought it back to dealer but the tech could not get it to repeat so I took him for a drive and he thought it might be another coil pack. The 60 day warranty is history so I don’t feel like shelling out $$ for them to tell me what they think it is!