Turns over but wont start

So my 94 chevrolet Silverado c1500 so after
driving it I went In somewhere for about 30 mins
came out and tried to start it. When I turned the key
it turned over but wouldn't start. I tried a few times
then decided to leave it for a while so I didn't kill my
battery. Came back the next day tried again and it
still just turned over and cranked so I towed it
home. I then checked all my fuses inside the cab
and checked the oil and it still wouldn't start. Well
later that night my brother told me to pop the hood
and check the fuses under the hood so I did that I
pulled a couple out and then he wanted to hear
what it was doing so I tried to start it, to my
surprise it cranked and started. So I shut it off then
started it and it started with no problem.  About a
half hour went by my wife drove it to the store and
back then it wouldn't start again. The next day I
unhooked the battery after messing with a few
things again and it started. I shut it off now it won't
start again. I have tried disconnecting the battery
again and nothing. Any ideas?

in the last year I have done the following repairs on
the truck.....
Replaced the
* radiator  *fuel pump * spark plugs and wires  
*master cylinder *distributor cap and rotor *clutch
kit *alternater * u joints  
So far I have Checked the fuel filter  and fuel
pump,the oil and water the fuses all of that was
good then I checked the coil and plugs to see if I'm
getting spark and there was no spark. Im lost