The car will run sometimes and sometimes it won't. on 1991 Saab 900

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The car will run sometimes and sometimes it won't. I can be driving along then all of a sudden the car starts to die. Sometimes it will die all the way out, then sometimes it will start to die then all of a sudden it will pick up again. When it does die out on me sometimes I can start it up again after a while, and other times it won't start at all. What is this? It's driving me nuts. It seems like it loses power. I need help. I mean the car needs help.
(1) Answer
I worked on an early 1990s SAAB that had this type problem and it turned out to be an intermittent failure of the fuel pump. I made the conclusive diagnosis with a fuel pressure gauge taped to the windshield and when the car acted up, the fuel pressure dropped like a rock. Generally, if the problem is Ignition related such as an Ignition module, it just shuts off cleanly and suddenly and won't restart for 1/2 an hour or so if at all. Fuel tends to be more of a loss of power, sputtering etc. If it is a fuel pump problem, then always replace the pump, pick-up sock in the tank, the fuel filter and fuel pump relay as one job. Many places will try to cut corners and the car will still have some weird problems down the road. ( A dirty pickup sock can be a total pain to diagnose )