OK, so I have a 98 ram 1500 318 4x4 auto. Every now and then when I have the cruise control at 70, it feels like the trans slips but when it does, I don't lose any speed. Could that just be the plenum being bad or the trans not rebuilt right? The truck does have 180k

 

Watch the tach when it does that. If it bounces about 200 RPM, and then drops right back, more than likely it is the throttle position sensor. Its just dropping tcc, and then re-engaging.

 

I'll check it out when I get out of work. If it doesn't, what else could it be?

 

Any number of things, from a cylinder miss, to a trans rebuild. Start with the little stuff first.

 

Well, today it did it once, no rpm difference, previous owner said the trans was rebuilt in 08. There are no codes showing at all. I used to have a random cyl 8 misfire but I fixed that when I did the cap and rotor. I do know as I said before, I do need to do the plenum still.

 

Mine did that. Usually up a slight grade or into a headwind. I thought it was the torque convertor but it turned out to be my speed sensor. EZ and cheap to swap in a new one.

 

Mine did a similar thing. Felt like it would stumble and then kicked back in real quick.

Turns out, it was the TPS as HeyYou mentioned. Cheap and super easy to replace. Hopefully that fixes it for you.