1990 Mercury Sable GS turns over but won't start

1990 Mercury Sable, 125,000 miles, 3.0 engine. I recently changed the water pump on the car without much hassle. While installing the new water pump I had the battery disconnected as the alternator wire kept wanting to touch metal and spark. I re-assembled everything but it doesn't want to start. It will continuously turnover but won't start. It will act liked it's flooded and spit and sputter like it's trying to start when you have a flooded carburetor. The car was starting fine before I changed the water pump and I'm banging my head on why it won't start now. One last thing, the car was sitting on a slope during the time of the changing of the water pump with the engine facing downwards, not sure if that makes a difference or not. Any help will be appreciated.

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