Someone made this comment as to why my 4dr '65 Volvo Canadian, B20B swap w/ twin SU carbs may be acting sluggish (copy/pasted exact post):

"My 67 had a similar problem, it would start to bog and chug at around 55-60 as well as going up hils. If I remember it was a combo of running lean and a sticking suction piston or whatever the hell it's actually called, the piston's needle was bent and itwas sticking and not moving in sync with the rear carb's piston. When it would chug up hill I noticed if I pulled the choke out giving it more gas it would perk right up and haul ass up whatever hill I was on. At least this is what I remember was going on, remove the air filters and manually lift the piston and see if it sticks at all or seats itself properly when comign back down.

Worth a look see."

My exact reply was:

"Hmm, I checked this as you suggested and my dampers are moving up and down freely, but are BOTH of them supposed to move TOGETHER??? My rear one seems to start opening up far before my front one...."

Can someone answer my question/reply for me??

Thanks!