2.8L Cutlass Code 42, Wont stay running...

I bought this car with a blown ICM, I replaced it and the car ran fine, but then it had a coolant leak out of the head gasket, so i pulled the heads, had them resurfaced and put it all back together with new gaskets... Started up and ran fine. At the time i didnt have any antifreeze so i put water in it. Well now the water is freezing. I had it running good yesterday, and was able to get a gallon of antifreeze in it... Today one of the rdiator hoses were kinda frozen, slushy... So i went and got a gallon of pure antifreeze, and started the car. It ran perfect for about 20mins, then it started to spudder, and died. I kept trying to start it, and a few times it would start, but it would backfire, and stall then die again... Ive noticed if i leave it for about 30mins, it will start and run fine, but after about 5mins, it stalls and dies... when it does that, the SES light comes on. Showing code 42 Ignition Control Circuit...
Sometimes when it dies it will crank but not start, or even sound like it wants to... I checked for spark at this time, and it has none... But again let it sit for awhile and it will start right up...

The coil packs are all good, and the ICM Ign. Control Module is from a junk yard, I assume its good to because I havent had any problems till now.

Please someone help... I dont want to get a cracked block or head because i cant get antifreze in it...

Thanks in advance

Pull the module and have it tested at AZ or NAPA, what year is this by the way?

I went to autozone to test it, but they said they cant test this one, something about there test equiptment not working at the time, im going to have it tested at another autozone this weekend...

Also its a 1988 VIN W

I would bet the crankshaft position sensor is failing. It provides signal to the ICM and to let the ECM know and in turn sends signal to the ignition coil when to fire. No signal from the crankshaft position sensor then there is no way for the ignition coils to fire.

It's a little bit tricky to replace the crankshaft position sensor. Once you get the connector out, you need like a pry bar to pull it out but slowly and be careful and not break that item. It has a strong magnet on it and that is why you need a pry bar to remove it. Make sure you get the right part for it because we almost put a wrong part given to use by the parts counter clerk. Installation is just the reverse.