please help

[kosovobandit]

I have a 99 6spd targa car with a blackwing, corsa touring system,
160 tstat, smooth bellow, MSD wires, air charge temp sensor relocator and recalibration, LS1 edit tune, and TR55 plugs. I have recently changed to plugs from the original to the tr55's. that was about a 2 weeks ago (Easter weekend) My old plugs were a little fuel fowlded. now I am getting a slight surge at idle, between 650-725 RPM. And I have picked up a slight backfire through the exhaust on deceleration. I want to ask if this is the start of fuel fowling. I am pulling plugs tomarrow. the weather in texas has been changing alot. give me a way to head. By the way no codes in the DIC.

[bill]

check the new plugs.they could be bad.make sure they are not cracked.