Hi, I have an '89 Raider 'Desert Runner', it's a 5-speed, 3.0L v6, with air conditioning. Two-door model with some little quirks but mostly it's running rich and it's been doing so long before I bought it as the catalytic converter is dead.
I recently replaced the engine temp sensor (the one that talks to the efi), cleaned the IAC, and the mass airflow sensor. I replaced the O2 sensor, and cleaned the throttle body. It also has new plugs, and a new cap and rotor. I replaced the vacuum lines and cleaned out the EGR and tested it. Lastly, I installed a new EGR tube as the previous owner had deleted it.

I read that the baffles in the valve covers can become clogged with oil buildup if the oil isn't changed regularly causing oil to be pulled into the intake, but I'm not sure if that is reliable information. I'm perplexed about what to do and where to look next. Is there a way to tell when the EGR should be operating? Any ideas are appreciated.

 

The only times when you get rich running condition is when computer does not accurately calculate amount of air coming into the engine. Based on your description you've cleaned the MAF. I'd recommend to check it once more to make sure the voltages on it are correct and that the air temp is sensor in MAF is responding as well. Not sure if you have manifold pressure sensor (MAP) on your model. Check that as well to make sure it operates properly.
As far as EGR operation, it should only open when engine is under load. If you manually open EGR valve at idle, the engine should stumble and die.
One more suggestion: just in case, check all the vacuum lines once more. Make sure they are routed to correct places. Having them go to wrong ports (even on the same end of the manifold) can cause things not to work correctly.