Diagnostic codes I retrieved P0421 misfire fuel comp catlyst, EVAP, 02 sensor, 02 htr, EGR does anyone know what these mean, if it's an easy cheap fix? thanks

Wow, did you hook it up to a scanner and get any codes? If you can post what the codes are, it would be simpler to digagnos

Spark plug, spark plug wire, ignition coil or ignition control module are all possible causes

http://www.obd-codes.com/trouble_codes/

scroll down to your code and open code. gives symptoms and possible fixes

I would start with whatever is causing the misfire. That seems to be the core of your emissions codes. Putting all codes together it seems to be clogged injectors vacuum leak. Seems to be causing stalling too.

sounds like you got a smaller amped alt then what was there.

Sounds like a distributor or timing issue, a common issue with these cars sometimes. Our Civic LX was giving us the same codes, We replaced the distributor and reset the timing... problem resolved. Not sure about the 2005 Civic year model, the ignition system may have changed with the newer models...

Only 1 code (p1401) means EGR Temperature Sensor problem. Bad Sensor or EGR valve may need to be replaced. Autozone has some ways to test your sensor and egr valve.
If you do have a bad sensor it is about $170 average. If you have a bad EGR valve it is about $150 average.
Hope this helps!!! Let me know if it does!
-Kevin from KCG InnovationsAuto specialist

This all comes down to the catalytic converters. More than likely you will need to replace both of them plus your sensors as well. This can become very expensive with OEM equipment. I would suggest you shop around and see which is cheaper but still has good parts. Hope this helps! Have a good one!

IT'S POSSIBLE! IF BOT, YOU MIGHT HAVE TO CHECK OTHER CODES, AND REPAIR AS NEEDED!

Your best bet , take it to a qualified repair shop .