My brother has a 2002 4x4 Dakota SLT 4.7 v8 that he delivers the mail in.

When cold it's fine but after a while it starts to slip. Once it cools down it's fine again. It's not overheating, it's just at operating temp.

I have not driven it so, I don't know if it's slipping or possibly dropping down gears at the wrong time or some other scenario that may feel like slipping.

I'm sure he isn't the first person with this, any ideas as to common problems?

Thanks in advance

OK I talked to him today and if he is gentle the slipping goes away but now it has developed the limp mode problem.

It was acting up a few weeks ago so he had the throttle position sensor replaced. It did better for a while but on the way to work today it went into first gear at highway speed and stayed there.

He went home and just before home it started shifting again but it was all over the place as to which gear it was gonna be in.

Turned it off waited and back on, no help.

Any ideas?

You need to pull the codes and post what you find.

Does the speedometer act up? Any lights like ABS/Brake/anti-lock lit up?

He is in another state and when he gets back to me with that info I 'll let you know.

Thank you for the help.

Limp mode is a fail safe mode to get it off the road.
That means there is some fault. Be it electrical or internal .

Ask if there is any whining in it once warmed up (indicates possible front pump failure)

That should be a 45rfe trans. Which is basically a A604 based trans. Aka all electronically controlled and monitored

If he has access to a Chrysler DRB Maybe take a look at clutch volumes.