I have my '87 starts and runs perfect. Lately I have noticed that when I am on the highway running 70 when I come to a hill or I am in a pulling place I am getting an occasional miss or skipping. As soon as the load is off it smooth's out again. I have all new plugs, wires, distributor cap and rotor. The one thing I have not replaced is the Hall sensor. A few months ago I was having problems where the car would start and run perfect for 15 mins then shut off. As soon as it cooled it would start and run 15 mins. I replaced the Hall sensor with a used one and the problem went away. I am wondering if I should replace the Hall sensor and the ignition coil. Maybe a upgrade for better fire.
Anyone have any ideas or opinions???
Thanks for the input!

 

hall sensors are essentially a position sensor so their typical fail is the engine dying as you noted. Misses under load are more symtomatic of a cold spark (ie weak coil, failing ignition powerstage amplifier, wrong plugs) or a rich mixture ie intake air leaks or blockage/exhaust, O2 sensor etc. Since it seems to run good some of the time, I'd rule out the mixture issues. Is this a turbo or NA engine? My sense would be to start by testing the coil then look at replacing the powerstage amp. Google Volvo PN# 3501921 for some insights.