Hoping you guys can shed some light into this issue.

I have 99 Ram 318 with a erratic/spontaneous surging at highway speeds. It doesn’t always do it but more the most part it does after a certain point.

I have already replaced the TPS sensor twice with a Standard brand as well as the IAC. I do have the brake light switch as I read that could be the problem but my brake lights work just fine. I can’t seem to find a vacuum leak that I can hear or see.

No check engine light either.

 

How much of an RPM change are you seeing?

 

I believe it’s like a 300-400 rpm jump.

Sometimes it does for a good 2-3mins consistent and then there’s times where it won’t do it for a whole 45min drive.

 

That may be overdrive going in and out..... any codes?? Maybe a pending code? (won't turn on the lite.)

 

None whatsoever. Drives fine for the most part if I drive it locally or on short runs.

 

Need to do some data logging, see what the pcm thinks is going on.

 

Gotcha. That’s something I would’ve like to avoid.

Just got back from a 40min drive one way and another 40min back and drove perfect. I did swap a NTK tps sensor but I don’t think it had much effect as the first drive it acted up on the long drive back yesterday.