If you run with faulty tandem for long time that can cause a problem to your injectors(clog them as you have a lot of oil in your fuel) maybe that’s why your readings are like this.
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The smoke could be the head gasket or for all of your symptoms also can be low pressure fuel pump vacuum pump(tandem)
You need to check if you have oil in your tank somehow or then you change fuel filter see if the fuel in filter is black, if so it’s definitely the tandem pump.
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