First of all, thanks to all who responded with very good suggestions, because of them I know a lot more about Volvos.
However, I have tried several things and feel I'm getting very close to what the problem might be.

Below is my older post, and below that what I have done lately:

"Any help will be greatly appreciated.

My car runs sluggish almost all the time, haven't been able to figure what the problem might be.

From a complete stop it accelerates normally as it is picking up speed, but when the turbo gauge reaches 12 o'clock it dies down as if it is gasping for air or chocking.

I floor the gas pedal and there's no immediate response; after a few seconds it finally engages momentarily and jerkingly (revs up to 3000 - 4000+ RPMs and the turbo gauge is up to 2 o'clock).

I have to do this over and over in order to pick up some speed, once it picks up the speed it runs smoothly again (2500 RPMs) until it gets to the point again where the turbo needs to engage, and again, once it reaches the 12 o'clock mark I have to floor it again.

My mechanic has not been able to pin point the problem, he claims all the codes read normal.
I have replaced the fuel filter and the air filter; and have cleaned up the air flow meter. Just don't have a clue as to what to do next.

One thing I have noticed is that sometimes (not always), when I am at a traffic light waiting, I see white smoke bellowing out of the tail pipe (heavy at times).

Any clues?
Thank you in advance."

The latest:
1. Disconnected the (PCV?) hoses to the oil trap, removed the "Y" fitting in between and found out it was restricted, cleaned it up and replaced, and the car ran a champ for about 5 miles, and then back to the old problem.

2. Removed the small vacuum hose from the "Y" to the intake manifold and again ran beautifully for another 5 miles or so, and then again back to the original problem.

3. While parked in the dark checking for arcing of wires I noticed that the exhaust manifold was glowing red hot,literately. Is this normal?, I don't think I have ever seen this on any other car.

Question:
I've read in one of these posts about "the breather box being clogged", is this the same thing as the oil trap?....if so, is this easy to replace.

Again, your valuable help is greatly appreciated.
My apologies for the lenghty post.