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I think I would rather have him mad at me than dead.
If he really wanted to keep it a secret he would not have told you.
Gasoline acts as a central nervous system depressant.
Here is the MSDS for gasoline
http://www.hess.com/ehs/msds/9950AllGradesGasoline.pdf
The gasoline could easily be causing his symptoms.
Hope this helps
RichC
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