Engine surges intermittently
 

a 2004 Mazda 3 ... surges strong at stops.
Occurs at random.
Does this mean a vaccuum leak or a dirty/malfunctioning sensor?

Might be your MAF, but that's just a guess. This could be a lot of different things. I would start easy and make sure you have a clean air filter and then look into possibly cleaning the MAF.

mine used to do this often, it has become rare now, but ive cleaned the maf, the tb, intake filter, and grounded the tp to no avail...