Chevrolet Repair: Hard starting, starter fluid, vacumn

Question
90 cavalier, 2.2L 160k.  for the last several months the car has a very tough time starting.  It just cranks, and cranks and cranks with the occasional backfire mixed in for good measure.  I have replaced the plugs and the wires, sprayed carb cleaner on the vacumn hoses to check for leaks, cleaned up the throttle body.  It seems to be getting fuel, as spraying starter fluid into throttle body did not help, battery was tested and had a good charge (though the alt is putting out too many amps).  Tested the codes and the Manifold air temp (MAT) sensor was the only thing that came up.  I would appreciate any direction you can give me.
                                    Thanks  

Answer
Hi Rick, Does the engine run at ALL. The only problem these engines had was the hose going to the map sensor in the rear of the intake. If it doesn't run maybe the cat-con is so plugged it can't get the exhaust out. If it does run how well after it is warm?

Let me know

Mark