Experiencing a thumping noise in the Transmission. Noticeable when OD is on, cruising at or about 1500 RPMs, if you increase the speed (RPMs), it sounds as if the vehicle is rolling over the warning grates on the edge of the highway. I was a Chevy guy, switched over to Ford. I truly like my truck so if any one has any input please let me know.

Update from Jan 17, 2017: Apparently the Turk converter has been an issue with Ford 5.4. The mechanic I took it too (who's opinions, and work quality) remains exceptional. At any rate he called it as converter shudder. There is a procedure that seems to be effective. Drain the fluid out of the transmission, change out the filter(s), re fill transmission, with motor craft transmission fluid. Here's the kicker, Ford has known about this problem, and lo and behold they developed an additive, that is used to prolong the velocity of the fluid. The normal cost start to finish around $350.00, time in/out (Approx.). 3 hours. More to follow.

shifting from 4th gear to overdrive slippage

I was on a secondary road and slowed down to 20 to 30 miles per hour to connect to the Interstate highway and accelerated to merge. At that point I felt two or three thumps in the transmission. Feeling that the tranny was going out, I took it out of overdrive and the thumping ceased. I accelerated to 50 and then engaged the overdrive and the problem disappeared. It worked fine the rest of trip. Last week I felt the same thump when the tranny sifted from 4th gear to overdrive. I eased up on the accelarator and the tranny worked fine when sh*ting to from 4th gear to overdrive. Yesterday, it did it again but this time I experimented with the problem by disengaging the overdrive and engaging again. Each time I did it, I felt the thump in the tranny. Any suggestions concerning the problem. I feel like the overdrive servo is causing the problem by not engaging the overdrive securely to prevent the thumping.