I'm guessing that you have the 5.4 right? Many of the power curves I've seen show that the engine's peak torque is somewhere around 3000, after that it starts dropping off(slowly though). And yes I admit I could be a little off on this.

Also do you pull with O/D off? Some people say to not tow in O/D but my dad and many others around here have always used it and wont be convinced otherwise. My dad's truck has over 150K and he has had trouble one time but thats because he forgot he had a heavy trailer hooked up and punched it at a light. All that did was throw a code, after clearing that at a local shop it hasn't had any issues what so ever. And that is the only time that truck has ever been at an auto shop.

Another thing, all of the hot rodding auto guys I know swear by Royal purple and their trucks and tranny's have been pushed extremely hard and are still going.

just my $.02

PS: txwolf, how'd ya like pedernales falls state park?
Haha, Txwolf ignore this, didn't see you had a separate post.

I usually have OD off while towing unless im heading down a hill or something (being in 3rd seems to slow the truck down). I cant see how your truck can pull that 36' trailer, have the TFT hit 200+ and still maintain a good speed. My truck just cant seem to do that.

I wonder if your transmission is "slipping" under load and with the fluid hot? Is it still under warranty? If so, set it back to stock, remove the Gryphon and take it to your dealer. I think they may need to "look" at it.

I think I'd do this even if the truck is out of warranty.

This doesn't sound like something I'd like to see continue, because it could be an early sign of damage.

You should NOT be having problems pulling a 5000# load. You'll certainly know it's there, but the truck was designed to do this task.

- Jack

Im not even running the gryphon anymore because I dont think it makes a difference stock or my custom tow tune. The truck is still under warranty, but im not sure they will do anything if i tell them that it has zero power when the tranny heats up.

I'd sure give it a try. The more I think about your symptoms, the more it smells to me like early indications of a transmission problem.

- Jack

I'm with Jack ... I'd take it in for service. You own a TRUCK, and it's made to haul stuff! :D If you're not able to pull a trailer that is well within the limits of what Ford says it can tow, it needs to be fixed. Plain and simple. :yesnod:

Alright, next time I take it in for service Ill see if they will look at the tranny.

thanks all

You should have no problem towing. I tow a trailer that weights about the same. I have no problems towing on flat or even holding the speed limits going up hills. I tow with OD off and I have up graded to a larger cooler. I have 40Ks on my truck and just serviced the tranny. The fluid looked and smelled like the new stuff but I tow a fair bit and I like to be sure that everything is good.Let us know what you find.

Im heading out camping this weekend so Ill see how it does. Ill check my tranny cooler to make sure its clean and working properly.

I dont tow with OD on, I usually have it off unless im heading down a hill. Ill see if i cant check the fluid as well to make sure it isnt too burnt. I wouldnt think it should be tho, I dont tow all that often.

Well i ran my towing tune and i must have something wrong with my head. The truck ran awesome. The tranny temp didnt get over 180 and it was about 33 degrees F outside.

I will have to get Bill to look at the 1-2 shift and 3-2 shift, seems a little hard under heavy acceleration.