95 blazer starting problems...of course

I have a 1995 blazer 4wd with 181000 miles. yesturday my blazer decided to ruin my day. i went out to start my car. this, being in the morning in northern NJ. it was like 45 degrees out. i turned the key, but my engine would start. i heard the humming from the fuel pump. the car was turning, but no start. i just recently did a tune up. about 2000 miles ago. plugs, wires, cap. i didnt do the fuel filter then. so i thought that i would do that today. i did that today and still the same problem. i just thought that i would try to jump start it. hooked it up to a wrangler, and walaa, it started. i turned it off to see if it would start up for me again. same thing happened again. just kept turning over without starting. my guess is that it is something electrical. battery shows good amps left. had it checked later that day. any suggestions??? thanks in advance, Brendan

same thing again this morning. im up for any suggestions of thoughts??