Confused

As I stated in my last thread I replaced everything but the kitchen sink my idle is still not right.I did the idle re-learn but did not help.Now the idle bounces up and down between 950 and 500.As a refresher I replaced control module,IAC,EGR, and TPS.Also I put new plug wires on,car is not throwing any codes so now I'M stuck.Any help or suggestions would be great,I want to try and avoid taking it to a garage. Thanks in advance.
Paul
Sorry it's a 93' 3.1

You have eliminated any possible vacuum leaks, poorly seated or bad pcv system? Throttle body vacuum leaks?

year and engine size please

year and engine size please
Sorry it's a 93, 3.1

As far as I can tell I have no vacum leaks,but am starting to think there may be a leak where the plenum meets the intake manifold.Is there any way I can test this before I pull the darn thing apart.As I forgot to mention in my first thread it is a 93 - 3.1.Also I can not find the PCV valve at the back of the plenum,that's where it was on my last lumina.

Spray carb cleaner or wd-40 around the seams between the upper plenum and the lower intake with the engine running. If the idle changes, you have a vacuum leak. What is the 8th digit of your car's vin? If its a W, the pcv valve should be mounted in the rear valve cover, about in the center. If it's a T, it should be in the intake, tucked under the edge of the upper plenum.