My 82 Westy just passed smog about two weeks ago. In preparation for that I had completely sealed the intake boot and all the other standard tune up specs. Plugs, wire, cap rotor, oil, timing rpm. With the tune up came improved performance but I also notice a more pronounced issue.
Upon load (acceleration- this would be pressing the pedal about a 1/4 way and holding it steady) the engine responds immediately, there isnt a "bogging" present but the response doesn't last into a strong acceleration, it kind of hangs.
My best description is a lack of fuel or an advance or retard of the distributor.
This "hang" lasts for about 5 or 10 mph of resistant acceleration then "snaps" into a strong normal acceleration.
I dont have a tach but it seems to happen in every gear about the same rpm band. It is much easier to detect in lower gears.
With this there is also a bucking at coasting/light acceleration when good and hot.(my van is to early for vanagon syndrome?)
She runs great at high rpms. But 55 mph/4th gear seems to be in that rpm band & I always seem to get "stuck" in that speed

I've adjusted the EGR linkage, lubricated the spring, adjusted the acceleration cable, cleaned and lubed the intake arm spring assembly, adjusted and checked the full throttle enrichment switch.

Can I get some suggestions where to go next in my troubleshooting??