Gen. 1 owners please reply !

I see you tried all combinations.
I'm wondering if you guys tried Tow-Haul while in Off-road mode with the rear locked?
Having the rear locked would create a little more drag.
I also didn't read that you tried manual 2nd and 3rd gears? Our 2010 can't lock out gears like the newer models.
But having read that someone with a newer one experienced the same thing I guess it doesn't matter but I also didn't read they tried locking out gears.
If you did and still experience a speed up, then my suspicions are true.

Ford wants to get you the most mpg they can.
The TB it's not opening up but rather that the transmission will unlock the torque management to allow for coasting.

While a Tune from one of our vendors is highly recommended, I don't believe it would completely solve what you have experienced.
But I've read that it will help with suddenly unlocking and start coasting.
SVC and JDM have factory style shifting just faster with more controlled shifting and not hunting gears while daily driving or erratic down shifting that the stock Tune has.
From reading through all the posts about Tunes, 5*'s performance Tune has the banging gears that some like.
5* also makes the performance Tune with stock like shifting. You have to tell them what you want.

I would also make a suggestion since you cooked the fluid that your have your brakes bled to add fresh better DOT higher Temp range brake fluid.
Not sure if Ford is using the best that is out there.

I thought the tow/haul doesn't activate when in off-road mode, thought it was one or the other. I could be wrong, haven't tried it

I didn't know or hear that either, would have to read the manual. You could be right.
I honestly do not remember all the ways you have repress buttons when switching modes and activating/deactivating other things like Tow haul, TC, RSC, ABS.
I honestly don't even bother with all that stuff until the snow, then I have relearn what the hell to do. LOL

It says HDC is not affected, I'm assuming you don't need to hit HDC again unles you do over 40 mph.

why not manual mode and select 1st gear?

The Car Stereo Company said:

why not manual mode and select 1st gear?

Click to expand...

2010 and he was in 1st gear

The reason I was suggesting a tune is that I'm pretty sure the coasting behavior (shifting and speeding up vs maintaining or decellerating) and shift points are different. Or maybe you have a tune and it sucks (but this sounds like stock tune behavior).

MTF said:

I didn't know or hear that either, would have to read the manual. You could be right.

I honestly do not remember all the ways you have repress buttons when switching modes and activating/deactivating other things like Tow haul, TC, RSC, ABS.

I honestly don't even bother with all that stuff until the snow, then I have relearn what the hell to do. LOL

Click to expand...

I stand corrected, I was able to have tow mode on and turn on ORM at the same time. In a 14' if that matters

Never thought of tow/haul and ORM good info thanks.

Thank you all for contributing to this post. I will try to clarify a few things..

The truck is a stock tune.

I was in 4-low, manual first gear. Both in and out of rear diff lock.

I tried it in and out of off-road mode.

I tried putting in into trailer mode while in any of the other driving modes.

There was the reply that states the throttle body may not have actually been opening. I suppose this is possible.. but it certainly did not feel or sound like it.. It was like clock work to the same high RPM before dramatically slowing the truck with what felt like chopping the throttle.

It was not in hill decent when this happened. I had already given up on that feature for this type of massive, steep long decent. And it as not braking that slowed the truck when it would finally decide to slow down. It was engine / compression braking.

What drives me crazy about it... it is not like the truck was not capable of creeping down the hill like all my other 4x4 I have wheeled with. Heck, I learned how to drive (steer) at 7 years old in my Dad's 1966 Chevy K20 that was in low side, creeping through the rutted pasture while he tossed hay bales off the back. I am well versed in "low side creep" LOL

When this thing "decides" to slow itself down and creep.. it would do it.. but only for a second.

To be very honest, this was not a safe situation for my family. The brakes were so hot they wouldn't stop the truck. The pedal was high and hard. I had to stop for bout 20 minutes to get it back..

I appreciate every one's input. My mind is open to any ideas and theories.

Also.. I have owned the truck 2 years and never had it in a mountainous area to even know there is a problem. Here at home, daily driving... it doesn't matter... BUT I SO LOVED THE MOUNTAIN OFF ROADING ! ! I GOTTA GO BACK !!

Here in Missouri, I do not have anything steep enough for long enough to take an after noon to test things out.

I am crazy enough to momentarily remove the intake tube and ride out by the engine to watch the throttle operation to know the truth in what is happening. But I can't find a hill big enough !! LOL

Thank you all for your thoughts and brain power. Hopefully. together. we can figure something out.