2008 Mazda CX7 popping noise at cold start up in the intake manifold

I have a 2008 Mazda CX7. I have a weird popping noise and a little smoke from the intake manifold area down below the throttle body. If I let the car run for a few seconds, turn it off, then turn it back on it doesn't do it again. The car has the 2.3 with turbo. I've replaced the intake manifold gasket, actuator valve, throttle body gasket, pcv valve, MAF sensor and the intake manifold runner control valve. I've cleaned the EGR valve and the MAP sensor. Confused. Any ideas on what causes this ?.