tow/haul mode question

[horse power]

I have an '06 F350 powerstroke that I use for towing my horses/horse trailer. When I have tow/haul mode engaged and I'm trying to maintain a slow speed (around 20 mph) my truck seems to have a difficult time selecting which gear it wants to run in. It will start to rev up and back down without shifting while I maintain a constant speed. It causes a fairly rough ride for the horses! It does not happen if I am accelerating or if I cruise along below 20 mph or over 20 mph just at 20 mph. It also does not happen if I disengage tow/haul mode. Just wondering if this is something anyone else has encountered and if it is fixable or if it is even abnormal. I can recreate the problem with or without the trailer by engaging tow/haul mode and going at that speed. Any input would be appreciated!

Thanks, Lisa

[Jason1Pa]

I don't think I've ever rolled along that slow for any length of time,but I am not a big fan of the tow haul. I never use it anymore. My biggest complaint is when going down a long hill you will want to use your brake at sometime right? Well,when you ease on the break it will down shift. Not so bad,but when you let of the brake( so you don't build up to much heat) you will find the motor slowly start to run faster as you continue. If you touch the brake peddle again it drops down another gear and really screams!! Drives me nuts!! There was a guy from International @ a local Ford dealer one time talking about all kinds of things and I asked him about this. he said don't worry it will handle it. Well,if it does thats great,but I'm not going to put it to the test... I do like it when going up long hills. Kind of holds it in gear longer instead of a lot of up down shifting. Also if you have to make a panic stop it comes in handy. like I said I never use it anymore. I haul Antique Tractors on a gooseneck and I'm loaded down a good bit(up to 15,000lbs with tractors and trailers) and I don't feel it is wearing away brakes or anything. My trailer is a 03 and has the original brakes (very little wear) My Truck is also a 06 with 40,000 miles and it has the original brakes still... You may want to just not use it anymore