RedRocket350

i have an lt1 in my datsun, and a couple of weeks ago, i started having this problem with the car. when it would start up, it would idle really rough for a couple of seconds, so i would hold the rpm high, then it would go back to normal. then, it would idle high sometimes, and low sometimes. now, i went to start it today, and the battery was dead(i do not know why, because i rewired the entire car with a painless harness. I have the vats module with the little red light on the top of it, and when i turn the car off, the red light stays on. Could that be whats killing the battery?) so i put another battery in it, and now it will crank but will not start. I was going to see if there was spark but it was raining. The fuel pump was kicking on too.

ss.slp.ls1

iTrader: (36)

Any codes?
Check the fuel pressure, even if you hear the pump priming, doesn't mean it's actually working.
Check for spark at the coil and at the plugs.