somethin wrong with my 5s, rpm jumps and drops Options

[mikew04]

while driving my car in any gear or nuetral, or any throttle position, my engine will sporadically jump and die. the tack will flick up 1 or 2k rmp from what its at, then flick down to zero, and go back and forth really fast. this is happening for about five seconds or so at a time, and every few minutes. it occurs less often when the car is warmed up. the tach seems like its reading the rpms right, the car will jolt back and forth when this is happening, and the car wants to die on me as the tach reaches zero. when the tach goes down the check engine light flashes on, like it does if you stall. i checked for codes, and its not throwing any. i have a spark on all cylinders, and my spark plugs were replaced and gapped correctly. i checked the power connections and the grounds and everything looks fine. this is making it really hard to drive the car, especially in this weather. thanks for any help.
-mike