1996 Volvo 850 Turbo "Chug"

[Thatbluegsx90]

I have a 96 850 causing me to pull my hair out, for starter a whole level 0 maintenance has been done but the issue happened prior to all that, my 850 almost feels like it's Chugging while at idle in park and more prominent in drive while stopped and you can feel it in acceleration slightly, it almost has a old small block sound/feel in a sense, Ive also noticed it takes a few more seconds to start up unless I press the gas a little bit... it idles steady around 800, 40psi of fuel(assuming I'm losing 1 or 2 psi with the 90°elbow I have to fit gauges) 155 +/- 5 psi of compression across all cylinders, all the engine vacuum lines have been replaced with silicone hoses. I recently got a O2 B1s1 slow response other than that I've never had a code. In my experience O2 sensors usually don't cause issues 24/7 (primarily work on GM vehicles) but I'm at wits end

[matthew1]

Check intercooler for cracks, and IC pipes down there for good fit.