Pulling CEL codes kills engine - 348

I have a 1990 348 started missing (cutting out ) and threw a check engine light. I never pulled the codes on this car before so read through all the threads. After holding the button down for 5 seconds I release it and about 2 seconds later the motor just shuts down. It almost seems as though when the ECU starts to poll it's memory it quits running. The whole engine shuts down. It's not like one bank shuts down and then just drags the other side down. Ok brotherhood let's see what you got!