I have a 1993 ford f-350 crew cab 4x4 5speed 181,xxx miles oil change every 3,000 miles since new. When I am deceleration it puffs smoke. If I hold the throttle open just a hair it doesn't smoke. It does not smoke any other time. No smoke at idle or wide open. runs great engine runs very smooth and quite. No blow by I am thinking its the valve seals Since it does it under high vacuum. I was going to replace the valve seals this weekend should I or am I wasting my time.

 

Sounds like the seals with that mileage and how easy it is to do just throw some new seals in and see if it stops.

galaxy S4 using IB AutoGroup

 

I would think if it was sucking it up past the rings it would have blow by.

 

Valve stem seals......

 

x4

You might want to check for sloppy guides while you have the springs and keepers off.

 

I put valve seals in the drivers side they all looked good. When I got to the passanger side I noticed all the plugs had crusty dried up oil on them and the #6 cylinder has 25 psi. What can go wrong in one cylinder and cause one side to burn oil? the drivers side plugs are clean.

 

I'm going to check the compression again. It was getting late last night I could have not done something right. also what is strange the truck never missed idle perfect.

 

#6 is the second plug on the drivers side...
If the passenger side has more sludge it is likely because fresh air is drawn in through the filler and the PCV is bringing vapor up through the passenger valve cover.
Glad you are going to check again.
25 psi is bad, very bad.