1997 Chevy Silverado Won't start

Two weeks ago, this truck just wouldn't start no warning. Just clicked so we replaced the starter. Then two weeks later, it sat without being started for 36 hours temps have been in the negative, HEAT was added to the gas tank Friday night as we suspect water was in the gas. Sunday morning went to move the truck and it won't start.

Starter engages and tries to turn over, almost caught and flooded out. Let sit for eight hours, tried again. Won't catch. This morning changed spark plugs still won't catch. Replaced fuel filter and checked pump. Filter filled. Have not tested pressure yet. Next step tomorrow after we get a gage.

At a loss as to where to check next. Can't afford to just start replacing sensors. Which ones will keep the vehicle from starting?