[Shotimes] cylinder not firing

[Matthews]

This just crept up the other day. When I start the car one of the cylinders
isn't firing. After about 2 miles it kicks in. Sometimes with a little
shutter when I'm driving or it starts firing while the car is idling with no
noticeable effect other then everything smoothes out. If I shut the car off
for a few minutes it will start with all cylinders firing. If it sits for a
few hours it will not fire on starting, but go the 2 miles and it starts
firing again. No smoke or anything weird coming out of the tail pipe. It
seemed more to me like a injector was plugged rather then leaking because I
wouldn't think it would take 2 miles to clear out the gas and it starts with
no problem. I checked all the front plugs and they are all
firing(naturally)so I know it's one of the rear plugs and I haven't had a
chance to spend the time trying to get those out. Any thoughts?

Mark