I have a 1990 accord EX automatic with 155,000 miles. While driving on the freeway, very intermittently all of the following happen. The tachometer bounces between 2,000 and 3,500 RPM (while cruising, it should be about 2900). Although the engine is obviously not fluctuating like this, at the same time it stutters a little bit while cruising. Also, a couple of times I have noticed the battery light go on for a second or two, and then turn off. The battery light doesn't go on while this is happening, but during the same trip. I just replaced the distributor a couple months ago, although the fact that I got a new distributor off eBay for $100 scares me a little bit.

Check Battery connections, The Battery ground to block and bond between body and block or battery. Check wiring from distributor for bare spot or pinching.

The BLU wire from the Ignition Control Module (ICM) goes directly to the tachometer. I suspect the ICM is failing--AutoZone can test it, and coils, for free on their Well's machine. Aftermarket distributors have been problematic to site members.