96 cavailier timing issue

My car has been getting really bad gas mileage lately, and it also has been stuttering and missing when accelerating hard. we hooked it up to one of the readers like what auto zone has and drove it around to see what numbers it was giving us. the first thing that came up was cylinder 2 misfire, and when we accelerated the timing retarded i think to almost -40. and then when we stopped it went back to around -8 i believe. so i and wondering if it is the ignition control module is sending the wrong communication, or if the knock sensor is bad because it should be advancing as we accelerate. only a few times when i first started it up did it feel like it was running on 3 cylinders, and then once it warmed up, it smoothed out. anyone have any suggestions?

When your engine misfires it jerks the motor pretty well, and the knock sensor is probably picking up a false knock and pulling timing pretty hard.

Replace your spark plug wires and plugs. If it still misses, replace the coil pacs.