I own a 03' Dodge Grand Caravan 3.8L. It idles horribly when sitting and driving. I recently replaced the idler pulley and fixed the whining noise but I'm afraid theres something more going on.
When I start the van it seems like it wants to stall. When I start driving, the van drives fine for 10 seconds then the engine bogs down and I have to hammer down on the gas to get it to go. I understand that doing this is not good for the van but being mine and my wife's only vehicle we need it to get to work. I got the error codes P0300 (multiple cylinder misfire) and P0172 (Fuel Control System To Rich)
What could be causing this, and how would I fix it?

 

Unfortunately there are many possibilities. It will be a process of elimination without a scan scope and real time data. First I would verify there's no vacuum leaks. That's often the culprit. You could start with fuel pressure. Should see 55psi at the test port on the fuel rail. Here's more info:

http://www.obd-codes.com/p0300
http://www.obd-codes.com/p0172 It states MAF sensor. You have a MAP sensor. Same function.