Not that you don't have enough things to consider..................................I feel compelled to give you another, if it passes scrutiny of some of the smarter guys you may want to give it a shot. Could it be a bad shut off valve or vacuum switch on the "ignition" assembly? Try disconnecting the hose to the shut off valve befor you start it next time. Just throwing it out there.

Good luck!!!!

__________________
Rich B

1983 300D Turbo
205k

Excuses are crutches for the weak