Rough idle startup?? help!?

its a 2006 subaru impreza wrx Sti. the idle struggles during warm startups. basically the idle stays/dips at 0 and the car shakes/feels like it almost stalls for about 5 seconds then goes up to normal. also sometimes the car feels like it jolts when im accelerating. there is no check engine lights and ive brought it to over 8 mechanic shops and none of them knows whats wrong. they all say "drive on it until it gets worse" but im sorry i dont want to get stranded one night. other shops had me replace the entire fuel pump/filter/selinoid/relay/etc, spark plugs, new key/chip for the immobilizer, and clean out the maf sensor/throttle body etc. Any advice will be greatly appreciated.