OBD1 Test

There are a total of four plastic lines in this part of the system. The red and green lines connect to the EGR (part of the emissions system) and the intake. The other ends eventually connect to some solenoids in the fender. The remaining two connect to emissions parts that pump air into the backs of the cylinder heads and the catalytic converters. Engine vacuum comes in from the line hooked up into the intake (green, I think), and the solenoids control if that vacuum gets to the three components. It's a weird setup, but works pretty well.

Take the intake hose off and you'll see the plastic lines a bit better. It's likely one has cracked or broken, so the computer can't control those parts.