engine surges then stalls at idle

I have a 1995 ford contour 4-cylinder with 165000 miles on it. I get a code 172 and 519. The car runs fine when going down the road,but surges and stalls at idle.This seems to be worse the more electrical load there is..ie: lights,heater etc. I've changed the oxygen sensor,throttle position sensor,fuel filter,alternater,cleaned out the converter,did a fuel pressure test,checked the egr, plugs, wiring and vacuum lines.I'd really like to keep the car going,its in great shape.Any help you can give me would be appreciated!!!