Tachometer Bouncing then stalling on startup

[josh18922]

I get in and start it up and the tachometer bounces between 500 and 1000 RPM then stalls.

Did this three times. Then, I put it in nuetral and it starts right up w/ no problems.

Oil Good
Premium Gas Always (Quarter tank in it) However, I did put a bottle of the Lucas gasoline additive in (first time ever).
Antifrieze level good.
Temperature: Normal

Anyone have any ideas what this could possible be?

[josh18922]

Also, does anyone know where the intake on the gasoline tank is?

Could being parked on a decline cause this?