My 94 Z28 is surges like crazy when it's idling, but i've noticed something new. Now it surges just a little at cruising speeds. Here's the kicker: It only does it when the engine warms up a little. Oh, and there is no Check Engine light on, or any other warning light for that matter. Please help me, could it be water in the distributer? Could it be bad plug wires? Could i be any more angry?