Problem seems to be returning..... Stalls or near stalls at idle,,,,, error code on two testers says cam sensor,,, but I put a new cam sensor on it when I did head gasket job,,,, anything can happen, new parts 'can' fail,, but what other demons can be going on, to fool the computer,,, that it thinks it is the cam sensor ,,,,,

 

I would look at the #6 piston first, (since that's your code) you could have a bad wire, plug, valve, or even a broken ring. Do a compression, and leak down test. Swap the plug, and wires, and see if the problem moves too.

If it's missing, and down on power, (due to age) it will definitely die when put in gear. One of the oboe tests should point you in the right direction. Could even be the wrong head gasket. h