Alright, here’s the thing: My '99 300M has recently begun stalling and randomly won’t start. I live in South Florida and the 300 has 77K on it. Have checked battery cables and tightened all battery connections. I replaced the starter a year ago and recently replaced the belts. Really can’t afford the dealer and don’t have a good local mechanic. Any advice and help will be much appreciated. Thanks 
Just wanted to add, it cranks fine, just won’t turn over. After about 30 minutes it’ll usually turn over. When it stalls, it’ll restart right away (so far).
Please everyone, cranking and turning over are the same thing! Ok?
This seems to be a fuel into the engine problem. It can be too much fuel, or, too little fuel going into the engine.
To clear a ‘too-much fuel’ condition, hold the gas pedal to the floor while cranking (turning over) the engine. As the engine starts, ease up on the gas pedal.
If it’s ‘too little fuel’, pull a small rubber hose off the big, black, intake tube. Spray a two second burst of Starter Fluid (available from an auto parts store) into the big black tube. Now, crank (cause to turn over) the engine. Don’t put you foot on the gas pedal, this time. If it starts, and runs a FEW seconds, have a mechanic check to see why.
The engine coolant temperature sensor (cts) is my first suspect. If the sensor gives the wrong temperature indication to the computer, the computer doesn’t know it. This won’t turn on the check engine light.
Thanks for the help and also straightening me out on the cranking thing.