Surging

I'll 2nd the "Surging is usually a lean condition" statement.
Now what's causing the lean condition is where the fun starts.
Could be crap in the fuel system ( easy enough to clean / check ).
Could also be a vacuum leak...( pain in the arse because it could be anywhere from the a/c controls to the brake booster to the vac advance canister diaphragm )

Is is surging on the hwy or idle?
Is this a daily driver or has the car been sitting for a week or 2 at a time ( or longer ) ?