[W126 Coupe] Slight miss-fire at idle

[Pavel]

My 560 sel has been in storage for winter since last october.  I have
started it for the first time yesterday to charge up the bat and let it
clean itself out a little. It started good but has a slight missfire when
in drive or just idling.  The car has just been overhauled completely about
3k miles ago and I just had it running perfect before I put it away. It has
new injectors, euro heads, euro camshafts, euro exhaust manifolds, plug
wires, dist rotor, distributor cap and a 3.47 rear end.
Anyways when it first started it idled high about 1100rpm then after 30sec
it would start to idle inconsistent would go from 1100rpm to 700 rpm and
back up to 1100rpm.  It did that for about 10 minutes and then it leveled
out at 700rpm with a slight missfire every few seconds(almost seems like a
vacuum leak but I could not spot one).  I noticed that I have a fuel leak
around the o-rings on the altitude box that attaches to the fuel dist,
would that cause the missfire?  Also I have bosch 4 platinum plugs in it,
should I switch them?  It ran fine with them before.
Another strange thing it was doing was, if you rew it up and let of the gas
quickly it rews down and than stops at 1000rpm for about 10seconds and then
goes to 700rpm.

PS.  I aslo stabilized the full tank of fuel in it before i put it away. So
I'm sure it has good gas. Again it is very slight misfire, but when you sit
inside the car you can feel the engine running, and that is making me very
irritated.
Pavel