Here's a problem that's been nagging me ever since the car was new. Right
now it has about 2500 miles on it. It's a 2006 V6 manual transmission
Mustang that has a intermittent idle problem. 2 trips to the dealer have
proved fruitless so far - the damn thing never acts up when I get it
there. *grumble* I hate intermittents, I'm not too car savvy, but I get
'em all the time as I work in repairing electronics.

Symptoms: When out of gear, engine will race up to 2K or so, then rapidly
drop off to the point where it almost stalls, then repeat ad-nauseam.
Makes shifting a real pain in the a.s... I'm assuming that it's acting up
when in gear, but it's not especially noticeable then.

Problem seems to occur right from starting the car cold, and will continue
all the way to destination - usually to work, about 16 miles or so. It
doesn't matter whether the engine is cold or hot. Here's the kicker: if I
shut off the engine, then restart it, the problem goes away for the
remainder of the ride! The problem is very intermittent, maybe once in
every 30 starts or so. Hopefully I've given enough information, but
there's something I've left out let me know. If anyone could offer some
thoughts on what could be wrong, I'd be most grateful - at this point I'd
be willing to try anything.

Thanks.