This is a good question but I don't gather much particular information from what you've written. I assume you replaced the MAP sensor for the problem you write about. You haven't given me any history of maintenance or repairs so I'll assume you haven't done any recently.
I'd recommend is replacing the fuel filter if you haven't in recent memory. Also check the intake air ducting for loose clamps or defects that would allow air to leak into the intake. Check the sparkplugs for wear or cracks, check the sparkplug wires for condition, if they are too old the resistance could be excessive or the insulation could be faulty, causing ignition failure under load climbing your hill. One other possibility is that the airflow sensor (MAF) is failing, that's not uncommon for this vehicle. Any of these items could cause the hard starting. Maybe a complete tune up is in order with a diagnostic check to look for electronics problems. Get a Ford expert to handle it, you need someone with experience and knowledge of the problems associated with your model and year vehicle.
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