There are two vacuum motors/switches mounted on the driver’s side in front of the strut tower. Both motors are fed by a white vacuum line from the intake manifold. One motor has a second purple vacuum line which goes to a motor/device mounted on the exhaust gas tube which goes over the front of the engine to the intake/filter plenum. The second motor has a yellow vacuum line which goes to the exhaust gas tube which snakes around the rear of the engine and eventually goes to the intake manifold. Perhaps this is for introducing heat into the intake manifold during cold starting. Each of these motors has a two wire electrical connector. I can’t find any mention of these components in my Haynes manual schematic. I wonder, what is the function of this whole system? Is it just to introduce warm air into the filter and air intake manifold? Is this unique to the 1993 model? I'm still trying to eliminate possible sources of my intermittent no-start/lousy mileage problems.