When I start up my car, 99' Fbody, I often get a pulsing or surging and the engine wants to idle real low, around 400rpm. It usually fixes itself, as the idle goes back up when it's warmed up, or it'll stall. Is this a common issue? Any codes that I should look for?

 

I have exactly the same thing as you. Don't know what it is either, but mines pulses/surges after braking too quickly after speeding up.

 

have battery, alt. checked. also check fuel pressure