The Drivers for the PTU are located in the ECU.. It sounds like a heat soak issue.. and PTU would be my first choice.. but that is not the case here.. so in my book, the ECU's drivers are next.. Rather than actually changing the ECU, you can open it up and hit it with 'Caned Air' to cool the Components down and see if it restarts.. the can is available at Radioshack type of stores..