See if the dashpot between the secondary barrel and the valve cover holds vacuum. If not, the secondary throttle plate won't open, and you'll have a very weak engine. It's a flying saucer thingy with a single vac line connection. The secondary has a mechanical interlock in the mechanical linkage, so it won't open unless you hold the throttle fairly wide open if you want to check for stickiness in the action, too. You can apply vacuum by mouth or with a hand held vac pump, like a Mighty-Vac, which can be bought for about $40 at parts houses, and usually includes a one man brake bleeding kit with it - quite a handy little gizmo. Test the dist. vac advance can while you're playing around.