Cylinder Misfire

I have a 2000 w/ 3.4 v6 and 56K. My check engine light is on and the idle is rough and wants to drop when stopped or at a light (a bit smoother if I shift to Neutral). It has rough acceleration but seems ok cruising at highway speeds. I had the computer scanned and got cylinder 4 misfire (forget the actual code #). Fuel pump was replaced last january so I was going to replace the fuel filter since I don't think the shop did. At first it seemed to be worse the the tank was low on gas (could this be bad gas cap? (couldn't be that easy)). I haven't bought a haynes manual for this van yet, so which cylinder is #4? Any ideas for a fix?

Thanks for the help,

Scott

1-3-5 are the rear cylinders starting at the passenger side. 2-4-6 are the front cylinders.

A misfire can be for any number of causes, including poor fuel delivery, bad injector, dirty air filter, poor compression, vacuum leak, fouled spark plug, etc.