I finally got my 81 Hatch GL to have the mid-range power I remember my 82 DL wagon having. There is a line coming off the vacuum seconday actuator, to a solenoid that vents the vacuum to atmosphere when de-energized. The computer wasn't opening the solenoid until ~3500rpm, so power would start to tail off, then come back on halfway decent to whatever I wanted to run up to.

While I was in there changing the intake gaskets, and a head gasket due to my screwup, so I clipped and plugged the line at the secondary actuator. Finally got to drive it today, and what do you know, the car came to life! Now, the power is very smooth from 1500rpm to 6k, and the throttle response is much crisper. It even sounds better, with a nice deep note when you stomp on it.

If you guys don't know what line I'm talking about, I can see if I can get a photo of it later today.

i got an 83 and i didnt relize that there was any computer operated things on the carb. i was pretty sure it was all vacum. cause im having problems in my low range rpms. i was thinking im have a intake manifold leak cause i have checked all my other vacum lines. so anyways maybe u can help me out on it. i have an hatachi carb.

Different models used different amounts of controls. Yours probably just has the standard vacuum solenoids like mine.

Usually, though, low end power issues are from either too free-flowing of an exhaust, or an intake leak. I would make sure the carb is tight to the intake, and use carb cleaner or an unlit propane torch to search for vacuum leaks.

do i got such a thing on my SPFI?

Nope, this is pretty much for Hitachi 2BBLs only, and as far as I can tell, they stopped adding that line in late 82 or early 83. I know on 84+, the secondary actuator had no provision for an external line. SPFI is a totally different animal.