Making a breakthrough!....I think
 

So I've been dealing with the bog down moan issue with my 2004 5.4 with 147,000 since I got it and have made several posts on here about all the possibilities. I even took video but you can't really hear it while I'm driving. The major pain in the ass issue is driving from 55-60 the engine moans like a motherf***** and loses power until I give it more gas. Well I turned the overdrive off and for once I didn't have the moan at 55-60. To me that was amazing as all the shi* I've done and money I've spent has not been able to get a proper diagnosis. So what do you think it could be down? Overdrive going out? Overdrive control module? Torque Converter? Here's a list of all I've done in the 3 months I've owned it. So all this is ruled out. The only thing I haven't done yet(ordered the part 2 days ago)is replaced the FPDM which will get replaced this weekend. Any advice and suggestions are much appreciated.:unsure:

New Spark Plugs
New Ignition Coils
New Throttle body
New fuel filter
Cleaned MAF
Re-flashed the PCM
Had Catalytic converters tested(were totally fine)
New seal around bottom of air box
Transmission flushed and inspected
New rear axle gasket and fluid
New Vapor Canister Purge Valve
New vacuum lines

I would wager your issue is with the CMCV plates that are on the intake manifold... The servo is either sticking or malfunctioning... The TPS sensor on the throttle body may also be mis communicating the throttle position causing this issue... The CMCV plates are like little throttle body styled plates that regulate air flow through the intake after it passes through the throttle body... A popular mod on mustangs is to delete them. But since our motors make peak power at lower rpm's then mustangs, it would actually hurt performance to try this..

Did your new throttle body come with a new TPS sensor, or did you reuse your old one?

Check your FPDM...

Ok good to know, this will have to be the next thing I look at. Is this difficult to replace or a very expensive part? When I replaced the throttle body it came with the TPS sensor so everything was fresh and new. After I replace the FPDM this weekend I'll look into the CMCV. Thanks