If I drive for a long time there would be alot of smoke coming from the back of the engine towards the firewall. It smells like burning oil. I don't see any oil leaks and theres never any stains on the ground.

I'd check the rear valve cover, it was leaking on my '94 Deville. Also the oil filter adapters tend to leak on the 4.9L engines.

Judging from your previous post I would also guess at a valve cover gasket.