Thanks for all of the excellent insights, gentlemen. I dug into this because after changing the fuel filters, the car wasn't building any power. As a result of my online research this weekend, I've fixed several vacuum leaks, vastly improved shift performance, cleaned out the boost sensor line, tested boost pressure, etc. I am certain that I wasn't getting any boost before this weekend, just due to boost lines and banjos being plugged.
I still have a serious smoking and power problem. More insights: It starts well hot and cold (25 degrees this morning without being plugged in) and idles very well. The power is good up to 2500 rpm and then it goes soft.
The entire fuel system is dry and without any apparent leaks. When I replaced the spin-on fuel filter, I installed a NAPA Gold and filled it with Redline before installing it. I didn't disturb the hand pump... I just started the car and it roared to life. Everything is dry so I don't believe that I have any leaks.
BTW, the smoke is whitish gray and is more visible the farther I drive the car i.e. it is ok on my street, but 1 mile away it gets worse. (This on an already warm engine.) Any ideas? Many thanks for all of your help.
90 Volvo 760T
88 Volvo 745 256000 miles!