2004 Chrylser Town and Country

First: nothing you stated nor any test results indicated that you needed a "new computer". It just makes things more complicated to replace a computer and then continue testing. The vast, vast majority of the time, the engine processor does not need to be replaced. Evaporative emissions concerns will generally not lead to excessive fuel consumption. Focus on engine performance. If you have a misfire, it's important to check the plugs and wires (as you have) and ensure good parts have been used to replace them. If you still have a misfire, you should perform a compression test on each cylinder and determine if you have a base engine or cylinder head issue. Misfires can also be caused by fuel injector concerns. Testing is needed to figure out what is going on. Once resolved, then you can perform diagnostic testing on the evaporative emissions system for that concern, if it remains.