[farewarning]

I have an 86 2m4 and I used to have the same problem. Id be driving and the car would just shut off. Then it wouldnt start just keep cranking. Then out of nowhere after like an hour it would just start. I had a mechanic change the ignition module and it helped for a little while but found my problem was in my powerbox too. that is the box of wire under the grill on the passenger side in front of the battery. one day i wiggled the box and it was fine. i remounted and rewired the box and havent had a problem since. It is prone to water being under the grill and also a lot of stuff builds up in the connections. In those stuck situations I found that holding the gas pedal to the floor eventually starts it sometimes. That is clear flood mode. First it would just crank then a little popping then start up and run fine until the next time. Also you might want to try changing your fuel pump if you dont hear it turn on when you turn your ignition. Hope that helps some.