You probably have three different, but related problems here.
1) Purple vacuum line supplies vacuum to the vent controls under the dash. This needs to be hooked up to a good vacuum supply on the engine or the vent controls will not switch.
2) Gray vacuum line runs from the vent controls in the dash to the heater control valve under the hood, inline with the heater hose. You need to connect the gray line to the valve, but it will not function until you restore vacuum to the vent controls. Are the heater hoses going into the heater core hot? If not, try moving the heater control valve by hand to see if the hoses get hot. I don't recall the default position for the valve, but I think default is open, so with no vacuum you should have heat. Check it either way. If your heater core hose is hot, then you may have a problem with the blend door in the dash. The blend door (GM calls it a temperature valve) is operated by a cable from the vent controls, so it is not affected by a lack of vacuum.
3) Lack of a high speed on the blower motor is usually caused by high resistance somewhere in the thick red wire that feeds voltage to the motor. The most common spot is a large black connector located in the engine compartment, usually near the pass side valve cover. Look for a thick gauge red wire going through this connector. This connector often corrodes and sometimes even melts, causing a poor connection that fails under high load. Unplug and check it. A lot of people just cut the red wire and either solder them directly or use a butt connector to bypass the connector.
