Trouble starting and revving when hot? How to get codes?

My '91 Civic has developed the following problem: On hot days, it sometimes won't start right up again after turning the engine off, but will do so after waiting 15 - 20 minutes. Most recently, another (related?) Problem has occured: Once the engine is up to operating temperature, it doesn't take well to accelerator pedal movement, i.E. It revs very slowly, sometimes sputtering, unless the pedal is pushed with extreme care. If I try to engage the clutch at this point, the engine dies, and although it doesn't take as long to start as it does in the hot day scenario above, it will usually take a few attempts until it fires up again. Any leads in this woudl be much appreciated!