My '94 850 wagon appears to be running well, but over the past week when I start it up I've noticed that the dash lights (everything you see turn on when you start the car) flicker on and off rapidly for a few seconds and then go out. At that moment, the RPMs drop about 100 RPMs and then recovers quickly. It'll do this for quite a while on my commute and then will eventually stop doing it. I've noticed that it does this mostly when I'm idling, but will sometimes flicker while driving too.

It looks like a failing ignition switch, but I have a new ignition switch installed, so I suspect that's not the issue. Besides, that's not likely to get better throughout a trip. What other parts can cause this kind of behavior that can recover over time? I'm wondering if the cam position sensor could be suspect, but I'm not sure what a faulty sensor would do. I recently replaced the fuel pump and filter, and have verified that spark, fuel and air are good. Any ideas would be much appreciated. Thanks.