Test the Mass Airflow Sensor with the engine running, tap the side of it with a screwdriver, and see if the engine stumbles - or, as just happened to my 2 month old MAF, the engine runs better. Also, try pulling the MAF out and giving it a good cleaning with Mass Airflow Sensor cleaner (ONLY). It'* not uncommon for a flaky sensor to cause the ECM to set codes for several other sensors. LOL
One major thing to check on the 3100s is the rubber tee that is at the front of the throttle body. That'* a common failpoint with the 3100s, and I've seen it on four different cars with that engine.
Some overlooked vacuum leak points: power brake booster/check valve, fuel pressure regulator connection, vacuum reservoir tank, heater controls (listen for hissing in the cabin near the steering column - very easy to overlook!).