Is it possible for oil to pass through the pcv valve? Mine has a crunching like noise and has oil residue left in the hose connecting the pcv valve and intake manifold

 

Absolutely. Over time, the valve can get fouled and not operate correctly. Many folks use carb cleaner to spray into the valve to try to restore the PCV valve back to proper operation.

 

Well I just replaced the plenum, new spark plugs, new distributor cap, and changed the oil. After doing all of that it ran perfect. Now after a few days of driving it seems like there's sort of a slight miss, it doesn't have the same tone or power it did a few days ago after replacing everything. I'm just wondering if the pcv valve can do that

 

Possibly. Try cleaning the PCV valve by spraying carb cleaner through it to get the gunk out of it. If the PCV valve is really old, change it out with a new Mopar PCV valve, as the aftermarket PCV valves don't tend to have the proper flow.

Also, since you've just removed the intake to take care of the plenum gasket, I'd check for vacuum leaks. Ensure all of your vacuum hoses are properly connected. Start the motor and spray some carb cleaner around the base of the throttle body and anywhere there are vacuum lines around the intake manifold. If you notice a change in idle in the areas that you spray the carb cleaner, you have found a source of a vacuum leak.

 

I wouldn't bother cleaning it, just replace it. Go to the dealer to get one, they were less than 10 bucks last time I bought one, and unlike the aftermarket fellers, they are actually the correct flow rate.

What plugs did you install?

 

I replaced it and it seemed to help a little, and I put Ngk plugs in it

 

Copper, or platinum.

 

I think they were platinum

 

I think coolant might be getting into the oil where the lifters are. When I changed the plenum there was coolant in there and everytime I start the truck, there's a white smoke cloud and then it goes back to normal.

 

Sounds like the intake gasket didn't get properly installed/sealed when you changed the plenum gasket. Coolant flows through the intake manifold gasket passages between the heads and the intake manifold. If the intake gaskets/intake manifold aren't properly installed, coolant will get into the oil. The most likely cause for this is the installation of the seals at each end of the intake manifold that come with the intake gaskets. These seals tend to space the intake manifold up too high and cause the intake manifold gaskets to not seal properly. I learned this once the hard way and had a bad coolant leak into the engine right after changing the intake manifold. Instead of using those end seals, I use a bead of RTV across each end of the block, let it sit and skim a bit, then install the intake manifold.