So I am moving to Arizona within the next few months and I plan on driving my '98 RS Eclipse the 2000+ miles from VA to AZ. Is this a Bad Idea? Last thing I need is having car issues on the way or when I get there. Also any help on refreshing or increasing gas mileage would be graet. Any tips or advice would be greatly appreciated. Thanks!

 

You will be fine.

 

Your 420a isn't as prone to breaking down as a modified 4g63 is.
I agree, you'll be fine. Replace both o2 sensors. The one by the cat is for the EGR and that may affect your gas mileage if the ECU gets erroneous data from that o2. The one closest to the header is the one that determines if your car will get more or less fuel, that's probably as old as the car.
Make sure you have fresh oil, fill your fluids, inflate your tires accordingly, and get your speed sensor checked.

 

You should be fine have a mechanic look it over and replace the o2 sensor in the manifold and replace the plugs and wires if they havent been done recently.