I have a 1988 Merc Sable. It has been having this terrible ignition problem for a long time. It runs fine for a while then starts cutting out. There is no spark during this time and then it quits running and will not start but after a while it will start sparking again and run fine. I replaced the ignition module several times but that did not make a difference. I cleaned the battery terminal where it connects to the computer. Lately it will not get a spark in the early morning while trying to start it for 10 to 20 minutes. Then it finely gets a spark. (a nice bright blue strong spark ), I f don’t let it warm up for about 20 minutes it will die out again on the road. And the same symptoms will return. Sometimes before it cuts out the speedometer jumps erratically to the end and back a few times like it’s shorting out but I do not know if it is related. This morning I tried starting the car but only got a couple of brief sparking moments and started up but cut out again. Then nothing at all till the battery was to low to crank the car any more. It seems to do this only when it is cold but it is not so bad if the car sits in the sun all day. It will usialy start right up but still needs to go through the warm up procedure before I can drive it.

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1988 Mercury sable v6