Your up hill starvation is classis clogged fuel filter. And if it's only happening when it's cold you must have some biodiesel or veggie oil blended in. If you're not running any biodiesel or veggie oil it's time for a new fuel filter. If you are running blended fuel it's time to cut it down some more. I typically switch to B20 when temps start getting below freezing at night, anything higher and you start experiencing hard cold starts and clogged filters.

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