2004 Chevy Impala Sometimes you have trouble starting it Usually have to hold it in order for it to start you took it to get a battery check and the checked out good so did starter and alternator.?

#1.Your problem is in the key switch engagement selonoid.You insert the key. Shake the shifter in park and maybe the car will start.#2.Your problem is in the netural switch selonid in the transmissiom.NOTE:May also be on the side if transmission.NOTE: AFTER one had made sure the battery is fully charged,gas in tank,starter working properly,fuel regulator valve in proper working condition.If all these are functional. Go to #1.