Help! What could be wrong with my 2001 Dodge Truck?

That's actually a very common problem with the 98 to 02 models with an automatic transmission. what you are feeling is your torque converter going in and out of lockup mode. It's actually caused by electrical noise on the accelerator pedal position signal circuit between the app sensor and the transmission control module when these vehicles get older. this noise makes the signal to the tcm less accurate so the tcm actually thinks your foot is moving up and down an the pedal when it's not. I know this probably sounds odd but I've seen it hundreds of times.

Good news is it's an easy fix. Most of the time you can fix this by simply removing and cleaning all the grounds on the vehicle. the battery ground cables where they bolt to the engine and the body ground cables. and actually take the battery cable connectors apart by removing the tightening bolt and clean the corrosion from there as well. Poor connection or corrosion at any of these places can cause electrical noise in computer control circuits.

If that doesn't do it there is another option. There is a company that makes an electrical box which transmits the signal directly from the app to the tcm which keeps the signal clean and crisp and solves the problem. I've installed at least 20 of them and they've solved the problem every time. Here's a link.

http://www.happibox.com/

Best of Luck !

[EDIT_ADD]

Hi "me".

We order the HAPPI BOX from the manufacturer online as we need them but I understand many Dodge dealers are actually stocking them. You might try calling dealers on your route to see if someone has one in stock. Otherwise I would try the customer service number on the website to see if they have a suplier on your intended route. Best of luck!

depending on the miles you have on the truck, I would bet it is merely the "throttle position sensor" is going bad. I have owned 6 Dodges with the Cummins TD with 5 of those being auto tranny. that is the only thing I have ever had to do to any of these trucks... all except my current one, had over 200K miles on them when I traded in on a new one just to get more features. I run lots of highway miles (like 40-50K a year) with about 15-20% of the time pulling a pretty good load... never shelled a tranny. take your truck to a reputable transmission shop and ask them to hook up their electronics to check the throttle position sensor and make sure you have $300-350, cause that's what it should cost to have it replaced, only takes them about an hour to do the work.

Maybe when it starts happening slow down 5 mph, then speed it 5 mph over hten what u were goin

have you checked the fuel filter and the air filter

In a diesel, the only thing that would make it run rough is lack of fuel, or low air