Sporatic Idling...need help

[MakDiesel]

I own an '81 280zx that has been troubling me lately. I've done all the work on this car since the day I saved it from the junk yard but I've finally run into an irritating little thing I don't know how to fix. When it cranks, the tach will jump from 750 to 1200 in little jolts but after around 1500 rpms it's smooth sailing. My problem may be related to a discovery I found yesterday. The hose labled "DIST VC" (the top one) connected to the charcoal (aka carbon) canister isn't connected to anything...and I cannot find the connecting end for the life of me. The hose runs all the way around the valve cover directly behind the fan and radiator and ends approx. near the throttlebody, but I can't find where to plug it up. Any answers fellow Z'ers? I included quite possiblly the crudest 5-minute drawing known to man but it's effective. Thanks in advance

[sblake01]

That hose should be connected with a T in the line that goes from the distrubutor vacuum advance to the front of the throttle body.

[MakDiesel]

The perpendicular branch of that 'T' is plugged with a golf tee (not my doing).....so that got me wondering, what DOES that hose do?

[sblake01]

That 'branch' is where the hose from the cabron cannister connects. That's how it is on my 78 280 and on my 79 810. It evidentally gets vacuum from the intake for both the carbon cannister and the vacuum advance.

[MakDiesel]

would that explain my poor gas mileage (20 tops on highway... and im not a lead foot most days) despite stripping the car of the front bumper, bumper shocks, air conditioning, and adding lightweight wheels?