the exhaust leak could be causing the cat efficiency code or you also have a bad cat to go with that exhaust leak. Idle control take out your idle air control valve near your throttle body and clean that out. Evap could be a number of things hopefully it is just your gas cap not being tightened all of the way, or it could also be the wires to the charcoal canister have become broken. Also one way yo try to beat the cat eff code would be to use a bong on the o2 sensor to move it further away from the exhaust gases.
Ok. Pete gets Karma great job peter...
A. [First bold] Make sure the car is not on when you remove it... Clean it with some gas .. Peter had the same issue on his car but it would just instantly goto 5k and keep rising... It's got a little black rubber plunger on the end of it and that likes to break down and become sticky.
B. Hopefully it is just your Gas cap for the Evap code..
C. I love the last paragraph of Pete's post, I would try Beer First I mean If the O2 sensor gets high that might bring it furthest away from the exhaust gases, but it might turn around and get addicted and want more... I say you get it drunk so it breaths that shit and has no idea wtf is goign on...
He is talking about getting a Spark plug fowler from autozone,, Drill out the center using a 1/2 drill [for the sensor to fit into..] Screw that into your exhaust and then put the sensor into the fowler it will move the sensor back a few inches and decrease the amount it senses.. Yet removing the CEL...
Marty