DTC -13 - O2 sensor open circuit.
DTC -32 - EGR circuit error.
DTC -33 - MAP signal high.
DTC -35 - Idle Speed Error.
From those I would check the wiring harness where it runs along the head and exhaust and under the truck to the O2 sensor. All of these codes can be caused by a short to ground on the five volt reference voltage side or by an open ground. That would also explain it being random, it would only quit when the voltage is shorted.
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Saturday, December 31st, 2016 AT 1:24 AM