I have a 1995 dodge ram 1500 5.2L rwd When I cruise at 40-45 or at 50 the truck starts to shake. it'll stop when i let off the gas or sep on it to go faster. I checked to see if the wheels were shaking and they weren't. I put brand new inner and outer tie rods new idler arm new pitman arm and new swey bar links and did the alignment with new front tires. It's still doing the shaking and i dont know what it is.

 

If you turn off overdrive, but maintain the same speed, does the shaking change?

 

I drive with overdrive off

 

I have the switch that shows o/d off when i push it the light on the switch turns on and shaking stops

 

That's an engine miss. When's the last time you had a tune up? Has the plenum been fixed yet? How old are the O2 sensors? Still have a cat??

 

I had a tune up about a month or 2 ago. The o2 sensors are new on it. Everything on the top end is pretty much brand new. And i shakes when i let off the break as if there is a miss fire so im guessing that's causing it to shake at that speed. And yeah i still have the cats

 

Need to check your plenum.