truck just shuts off?

Hello, sounds like a whole bunch of repairs made without much testing; it's kind of all over the place. Testing needs to be performed to find out what is missing when the problem occurs: Fuel, spark or air through the intake -- or if there is too much of any of it. Only then can you narrow down to the cause of the concern. This forum cannot help diagnose your concern, and as convoluted as things are with repairs having been attempted already, it will be more complex even hands on to figure out what is going on. It will definitely take someone with more skill checking this concern, as it is OBD I and less transparent through testing and diagnostic tools than an OBD II vehicle.