I have a 1990 chev 1500 5.7. And for about two years now iv been battling this starting issue. the truck would start usually when cold, but when hot it might take two or 25 tries. it doesnt turn over and I hear the starter clicking, eventually it would turnover and start. Now it wont start at all, and it has a new starter and batt.

SOURCE: 1990 chevrolet 1500 pickup starts hard when cold

Most likely the coolant temperature sensor for the vehicle computer. Secondly, could be the tps sensor "throttle position sensor" not registering correctly or perhaps lots of other things but most likely the coolant temp sensor.
Dale

SOURCE: I replaced my starter for a 98 chevy suburban 2

Possible not shimmed correctly. The starter teeth have to engage correctly for the starter not to hang up. That's what probably happened & broke teeth off. You had better check your flywheel around the entire circumfrence as teeth may be missing from it as well. Starter won't engage if teeth and flywheel teeth in same spot are broken off. If the flywheel teeth are bad, it will be a spendy fix to put a new one on... Rick

SOURCE: turns over but wont start

you need to find out if your missing spark at plugs or fuel pressure,you could hear the pump but that doesn't tell you if you have 5psi or 55psi,
you will need a fuel preesure gauge and check that on the fuel rail redd valve if you end up having spark

SOURCE: 2000 chevy express 1500 van having starting issues

Start with fuel system. Listen for fuel pump humm at fuel tank No humm check wiring to pump for power. Then check for spark at plugs and wires. Remove wire from coil and hold near engine and see arch when you crank. No arch. Replace ignition Modular inside distributor cap or cap or rotor

SOURCE: 2006 Chevy Cobalt wont start.

Check your battery, make sure terminals are tight and clean. If terminals are corroided, pour name brand coke a cola over terminals; the acid will eat away the corrosion. If this does not work, check connection to starter. If starter connection are good and you are sure battery's good, then your starter is bad.