I recently bought a 91 z28 and whenever i go WOT, there is oil that spurts out of the dipstick tube and gets on my manifolds and smokes. Could this be a bad pcv valve or worse?
Any help would be appreciated.

You have alot of backpressure. could be caused by many things.

Start with PVC is good
then check the breather tube that goes back to the intake.

And reason you have back pressure is bad piston rings I would guess.

I had the same problem in my 91Z28, but the problem was that where the cap for the dipstick and the handle meet, they were seperated. I put some super glue and electrical tape around it and haven't had the problem since.

Definitely check the PCV valve, the hose it connects to, and the port on the throttle body the hose leads to. They can all get serious carbon issues and usually will require removal of all three components (PCV, hose, and throttle body) for cleaning. There was a 1" slug of gunk blocking the PCV port on my 88's throttle body when I bought her.

Thanx for the advice,
Is there anything else i can try without having to pull everything to service the piston rings? When I start the car, there is a puff of smoke that comes out, then i can rev the engine as much as i want and it doesn't smoke. Then, while im driving, the oil pressure goes from 60 at idle down to 30 at idle and smoke starts coming from under the hood. I see oil all around the passenger side, mainly around the dipstick tube. None of this happened until i changed the oil. Any suggestions? Is it going to be easier to change the rings with the engine in or out?

Well Mr Brandon P JUST To let YOU know your piston rings are well how can I put it nicely.......FRIED. Time for a rebuILD pal so be ready to dish out some green. by the way welcome to the boards my friend.