I am sorry I caused such an uproar.

I usually give more information than I did before.

I also have been doing some internet searching during the post I made.

I do not have a CEL on, but I did check for codes:

231 - Long term fuel trim at partial load
232 - Long term fuel trim at idle

The black smoke just started, and occurs while driving, but worse at idle.

I also noticed it does not have the pickup it usually does.

I have had the car for five years (since 150k) and have always used 87 octane.
The previous owner had it since new and told me he did the same.
I have tried 89 but did not notice any difference so went back to 87.

I did put some Lucas fuel treatment once about six months ago.
Plugs have not been changed for a while.

My first guess was the Oxygen sensor, but do not want to replace it if I do not have to (see thought #2 below).

The Fuel pressure regulator is also up there.
I read on an internet search to prime the fuel pump and turn off key.
Then pull the vacuum line to see if fuel comes out. If it does, then the regulator is bad. Does this sound right?

It looks like to replace it you have to pull the fuel rail off, correct?

Funny thought #1 - I participate on a Mainframe (computer) forum like this. Many posters do what I had done and it really bothers me.

Funny thought #2 - I am in the process of changing the head gasket on my wife's 98 S70 T5. It is alarming. I have been doing a lot of research and have been taking lots of notes (even typed them up for myself). I just got the head back from the machine shop, and all the parts come tomorrow. My father in-law and I are going to put things back together this weekend.

These two Volvos are my third and forth, and I do most of the work myself with the help of sites like this.

So thanks for all of your help and please be patient with me.

Dave