Runs Good- Runs Bad
 

This is my 1st CTD so I'm not sure of the power, noise, and vibration this truck should have. I just had the tranny rebuilt, the rear end was popping so I changed the fluid, and I just changed the fuel filter. When I changed the filter and rear end dope, that night and the next day the truck drove like a caddy with a cummins. Then the next day it had more vibration and did'nt run as smooth. It seems like when it is cooler it runs better, but when you accel to about 2k rpm's it vibrates a bit and at idle /drive too. But there is no telling how it will run tomorrow. What would cause the truck to be so temeramental?

???
 

Wilderness are you getting light colored or white smoke when the truck is running bad?

Dave

On the rear end, you need the friction modifier. Just a couple ounce bottle, to add to the the lube.
On the bad running, it could be several things.
The rubber fuel lines get old and start sucking air, causes all kinds of goofy things, like hard start, poor performance.
How many miles? Could be sticky injectors, slipped timing (the smoke color answer will tell us a lot) or overflow valve.
Check all the inexpensive items first.

Yep, it's worse in the morning. And I added friction mod. But I used 90w "limited slip gear oil. Should I go to 140w inthe dana 70. The smoke is light and white by the way and it smells ritch. The truck has 160k miles now and I have no idea of the history.