Sometimes when I start the car the idle jumps up and down than almost stalls than goes to normal drives normal with no problems.I also notice while this happens I hear a noise from the back of the car sounds like a pump sucking for air or fuel (fuel pump) but if I give it gas it runs fine wouldnt you think if it was the fuel pump it would run horrible all the time not just at start up 1-5 times.

 

Have you checked your intake?

 

check what on it ? the car runs perfect after the initial start.Ive replaced the cat behind the engine after the manifold and both o2's up.New air filter and tune up to come once I figure out this issue.