This sputtering thing is driving me nuts! It idles fine, runs fine over 2800 rpm, but between 2 and 2800 or so, it seems like the engine is cutting out or missing or something. Seems like it gets worse after it warms up. I've changed plugs, rotor, distro cap, fuel and air filters and searched for vac leaks. Any help appreciated! Thanks

My '84 did this. Turns out that it only happened with less than 1/2 tank of gas. The reason was the pump inside the tank was sucking in air, which caused the miss. In my case, the miss only seemed to happen at about 2000-3000 rpm as well, so I wasted all that time changing everything you did as well. Not sure if this is your problem or not, but it's worth mentioning.

This is the most knock-sensitive region of the RPM range - have you checked your timing lately? Should be 12deg +/-2deg BTDC. And what grade of gas do you run? I have my timing slightly advanced, and I need to run 89 to avoid knock-sensor retardation (which feels like hesitation or missing as the timing is pulled back in large chunks.) Try a tank of the super 94 stuff and see if the problem continues. If it does, check your knock sensor to make sure it's working - the procedure is in Haynes, put key in position II with engine off and backprobe knock sensor looking for 2.5-5.0V, I think. I had the ignition control unit go bad on my '83 (wouldn't provide the proper bias voltage for the knock sensor), so the ignition was retarded at random all the time.

is it worse on hard acceleration? That is the speed where you need the most spark under a heavy load. Perhaps a wire end arcing internally, or a coil that is not putting out its full 40,000 volts. Try spraying water at the plug wires (at the spark plug end). If the engine misses on one cylinder there, inspect the wires closly for arcing. To test the coil, pull the coil wire while the engine is running- the spark should jump strongly about 1/4 inch past the end of the coil tower. (Eliminates the need for a pacemaker if you hold the wire wrong)