2001 Mitsubishi Diamante that cranks but wont start. Initially the valve cover gasket was replaced along with the 3 spark plugs (other 3 plugs located elsewhere not changed). It worked for a couple days then battery died and was replaced with new one. It worked for a couple days then crank no start, replaced distributor cap and rotor, it worked for a couple days, crank, no start. Two days ago I sprayed starter fluid and it did not start. The battery sounded weak so I removed and charged overnight and the next day the car started. I shut off and restarted a couple of times and all was fine. I drove 100 yards and the car shut off. I attempted to restart but it would immediately shut off or shut off when I put it in drive. I drove back with car in drive and foot on brake. I started the car yesterday and it seems to be running fine, today crank no start.
Sounds like the IAC idle air control valve may be sticking if you have to hold the gas pedal down to keep it running. May also have a loose connection of the air inlet hoses at the throttle body and or air filter. Any check engine light on, check the codes first. A weak battery will cause issues, if it is old have it load tested and replaced if needed. The throttle body should also be cleaned on the inside.