I have an '85 Buick Century (Grandma's car) with a 2.5-liter four cylinder engine and an automatic transmission. It has starting problems when the weather is hot and humid. Fortunately I live in MN and experience this condition only five days out of the year.
The problem is that the engine turns over but will not start. Also, on occasion it will start but then die. Under normal conditions, like 30F below, the car starts the first time and the engine idle speed is fine. I have replaced the fuel filter, air filter, plug wires, plugs and battery. Oh yeah, the muffler too.
It seems as if the engine is not getting enough gas. Sometimes we can catch it before it dies and rev the engine a bit.
The cause of a problem so intermittent can range from a poor ground circuit to an ECM (Electronic Control Module) having a bad day. The fact that you have gotten it running and it seemed to be starving for fuel along with the effect temperature has on the condition would direct me to begin diagnosis in a particular area.
The first step would be to install a fuel pressure gauge and test for correct pressure and volume. The pressure should be between 9-13psi and the system should be able to deliver .5 pts (.25L) of fuel to the fuel injector mounted on the throttle body assembly within 15 seconds. If not, a weak fuel pump may very well be the culprit.
The next step would be to analyze all the computer data with the use of a Scan Tool while paying close attention to coolant and manifold air temperature. If nothing shows up and the ignition system is functioning properly it can take several trial and error attempts to repair this type of sporadic failure.