Weird problem Hessitating....

Ok after i ran my car for a few mins today i hit the gas and at about 2500 rpm i am having a hessitation for a second then the car picks up, then it may do it again.. This has been goin on for the past 3 days. I pulled the plugs out and they have a white chalky look to them, i belive that means its running lean>?
My motor mods are
cold air intake
24# inj w/mass air
70mm TB
Trickflow street intake

All of these have been on the car for atleast 7000 miles.
The car has 170,000 on the motor
I also changed the plugs jus to see if it would help and it didnt.
Any ideas what it could be???
Could my fuel pump be taking a dive?? (fuel FILTER has about 7,000 on it also)