I recently purchased 05 F-150 4.6 litre 4x4 with 170 k. I changed the plugs but two of the threads were oily , what could cause this? I will be using this site quit regularly, I tend to DIY most maintenance items, thanks for your help. C.

 

If just the threads were oily it sounds like there was oil in the spark plug hole that got there from the outside. Would suggest you clean the spark plug holes good and reinstall different plugs in those holes and see what they are like after say 1000 miles.

 

I have rough spot revving around 1800 RPM kind of bouncy best way to describe same motor, any ideas ?

 

Can you do this?
Have someone raise the RPM to the point you feel something unusual, 1800 RPM ?
and hold the RPM steady while you go to the back of the truck and feel the exhaust. You don't have to get too close so as to burn your hand, but close enough to feel if there is a steady or irregular puffing from the exhaust. You should feel a steady flow of exhaust with no pops or puffing. If you feel a puffing it very likely is a misfire.
It has to happen regularly for the Check engine lite to come on. Let us know what you found.

 

I check exhaust pipe thru that RPM no pops or vacuum. ?

 

That would kinda rule out a misfire.
Have you changed the fuel filter recently? If not, may be a thing to consider.