2001 expedition, 4.6 triton, 118,000 miles. In the last week has become difficult to start when engine cold. Owned since new and always started on 1st crank. 1st crank doesnt do it anymore. Battery is strong and charging system good. Runs normally when finally starts. No fault lights whatsoever. Recent tuneup 6 months ago. I replaced fuel filter again, airfilter, bottle of Heat and fuel injector cleaner in the tank and full tank gas but no improvement. Is there a fuel system check valve that could be bleediing down? Also thinking fuek pump but it runs normally once started. Dont want to pull the tank if there's other areas yet to look at. Thanks for your time.