another thought along the fuel line
how long has it been from when it quit running to the last fill up - maybe a bad dose of fuel? How bout fuel filters - how long have they been in there? Are you able to check the "start of delivery" timing. Also, while you are in there nosing around with the valve cover off take a really bright flash light and inspect down where the chain guides and tensioner are located. See how they look. After thinking about it some - I don't think it would turn over if it was a broken chain type of problem. One of the techs will have to verify this. To me it is pretty simple to pull the valve cover. Be careful too in trying to start it alot - I burned up a starter on an old Chrysler that would not start one time.