Tried everything - Tacoma still won't crank...

(1997 Tacoma 2.7 L 5 speed 4 WD regular cab )
Okay, I'm completely out of options, so I hope you guys can help...
I get one loud click when I turn the key. There wasn't any warning , was running great ( as always) and then this. So, started out by replacing the starter, but that didn't help... checked the battery, and that tested good (12.51 volts), but ended buying a new one just in case the cold crank amps weren't enough. Cleaned all battery connections. Tested the alternator, and it's good with 14.18 reading with engine running and high beam lights... at 1500 rpms I get a steady reading of 14.15, and 14.22 with the lights off, and that was on the old battery. I have tested the starter relay, clutch start switch, negative,positive and ground connections to starter, and they are all good. I even opened up the new (refurbished)starter to make sure the contacts were good, and they only show minimal wear. I don't know where to look beyond this point... one more thing - the truck fires right up with a push start, and runs like a champ!

 

Bump! My truck is doing the one click thing as well

 

Did you check the fuses? You can still get power with a blown fuse

 

The other day I crossed a flooded road. It got to where the wake from me moving forward was splashing over the top of my hood. Didn't cause any immediate problems. Since then I haven't had a problem until yesterday. Everything has been fine and then I got in my truck to go to lunch yesterday. It clicked once when I turned the key. Tried again and it fired up. After work (approximately four hours later) the same thing. I had my mechanic check it and he said it was a bad battery but my alternator is putting out the right amount. I went and bought a new battery and went to start it and it clicked once with each attempted start (tried five or six time) and on the last attempt it started. When it started I let it run for about 10 minutes and then killed it. Immediately after the truck would start up every time. An hour later I tried it again and the truck barely started. I have no clue what it is. Any help is appreciated.

 

You still didn't answer if you checked to fuses over not. I had a short and blew my IGN fuse and it acted the same way

 

What fuse do I need to check?

 

Anything related to starting the truck like IGN fuses.