1979 242, lambda sond, b21f engine. car was given to my gf and it is in great shape, it has been very reliable, when she got it I notices a vibration at low rpms. later I replaces the UV joint closest to the nose cone of the Automatic tranny to fix the problem. I have replaced the o2 sensor, fuel filter,plugs, wires, rotor,cap primary coil, alternator brushes, steering rack, in-tank pump,main in-line 12v pump,fuel filter, a couple vacuum lines, change the oil/filter on reg basis. It has a miss under load, a hesitation that is stumping me. I checked the timing for the first time yesterday and it was at 20deg btdc!! I retarded it back to 8btdc (what the sticker says under hood) when I check the timing the mark does not do anything when I pull off the vacuum line off the advance capsule, could it be frozen in the advance state? i'm almost out of adjustability on the throttle/idle adjustment screw, that is why I question that. I think the next thing for me to replace is the reluctor and pick-up coil in the dist. what about the ignition control module? could that be bad? I always thought those were working or not, no inbetween. I have the hanes service manual so I have schematics. I want to completely rule out ignition before I go into the realm of fuel injection. thanks in advance for your help!